start-ver=1.4 cd-journal=joma no-vol=135 cd-vols= no-issue=10 article-no= start-page=106504 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250904 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Terahertz Field Control of Electronic-Ferroelectric Anisotropy at Room Temperature in LuFe2?O4 en-subtitle= kn-subtitle= en-abstract= kn-abstract=Electronic ferroelectrics, with polarization ? induced by strongly correlated charges, are expected to show ultrafast, huge, and flexible responses required in future optoelectronics. Although the challenges for ultrafast manipulation of such a polarization are ongoing, the expected advantages have been unclear. In this Letter, we demonstrate an unprecedentedly large increase by a factor of 2.7 in optical second harmonic generation at room temperature in the prototypical electronic ferroelectrics, the rare-earth ferrite LuFe2?O4, by applying a terahertz field of 260??kV/cm. The transient anisotropy indicates that the direction of macroscopic polarization can be controlled three dimensionally on subpicosecond timescales, offering additional degrees of freedom in controlling polarization. Although the polarization response is in phase concerning the terahertz field, its sensitivity increased with delay, indicating that cooperative interactions among microscopic domains play an important role in the unprecedented response. en-copyright= kn-copyright= en-aut-name=ItohHirotake en-aut-sei=Itoh en-aut-mei=Hirotake kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MinakamiRyusei en-aut-sei=Minakami en-aut-mei=Ryusei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YuHongwu en-aut-sei=Yu en-aut-mei=Hongwu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsuruokaRyohei en-aut-sei=Tsuruoka en-aut-mei=Ryohei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=AmanoTatsuya en-aut-sei=Amano en-aut-mei=Tatsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=KawakamiYohei en-aut-sei=Kawakami en-aut-mei=Yohei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=KoshiharaShin-ya en-aut-sei=Koshihara en-aut-mei=Shin-ya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=FujiwaraKosuke en-aut-sei=Fujiwara en-aut-mei=Kosuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=IkedaNaoshi en-aut-sei=Ikeda en-aut-mei=Naoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=OkimotoYoichi en-aut-sei=Okimoto en-aut-mei=Yoichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=IwaiShinichiro en-aut-sei=Iwai en-aut-mei=Shinichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= affil-num=1 en-affil=Tohoku University kn-affil= affil-num=2 en-affil=Tohoku University kn-affil= affil-num=3 en-affil=Institute of Science Tokyo kn-affil= affil-num=4 en-affil=Tohoku University kn-affil= affil-num=5 en-affil=Tohoku University kn-affil= affil-num=6 en-affil=Tohoku University kn-affil= affil-num=7 en-affil=Institute of Science Tokyo kn-affil= affil-num=8 en-affil=Okayama University kn-affil= affil-num=9 en-affil=Okayama University kn-affil= affil-num=10 en-affil=Institute of Science Tokyo kn-affil= affil-num=11 en-affil=Tohoku University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=111 cd-vols= no-issue=6 article-no= start-page=064502 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250204 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Josephson effect and odd-frequency pairing in superconducting junctions with unconventional magnets en-subtitle= kn-subtitle= en-abstract= kn-abstract=We consider Josephson junctions formed by coupling two conventional superconductors via an unconventional magnet and investigate the formation of Andreev bound states, their impact on the Josephson effect, and the emergent superconducting correlations. In particular, we focus on unconventional magnets known as ?-wave altermagnets and ?-wave magnets. We find that the Andreev bound states in ?-wave altermagnet and ??-wave magnet Josephson junctions strongly depend on the transverse momentum, with a spin splitting and low-energy minima as a function of the superconducting phase difference ?. In contrast, the Andreev bound states for ??-wave magnets are insensitive to the transverse momentum. We then show that the Andreev bound states can be probed by the local density of states in the middle of the junction, which also reveals that ??2??2- and ?-wave magnet junctions are prone to host zero energy peaks. While the zero-energy peak in ??2??2-wave altermagnet junctions tends to oscillate with the magnetic order, it remains robust in ?-wave magnet junctions. We then discover that the Josephson current in ?-wave altermagnet junctions is composed of higher harmonics of ?, which originate a ?-Josephson junction behavior entirely controlled by the magnetic order in ????-wave altermagnets. In contrast, the Josephson current in Josephson junctions with ?-wave magnets exhibits a conventional sinelike profile with a fast sign change at ?=? due to zero-energy Andreev bound states. We also demonstrate that the critical currents in ?-wave altermagnet Josephson junctions exhibit an oscillatory decay with the increase of the magnetic order, while the oscillations are absent in ?-wave magnet junctions albeit the currents exhibit a slow decay. Furthermore, we also demonstrate that the interplay of the Josephson effect and unconventional magnetic order of ?-wave altermagnets and ?-wave magnets originates from odd-frequency spin-triplet ?-wave superconducting correlations that are otherwise absent. Our results can serve as a guide to pursue the new functionality of Josephson junctions based on unconventional magnets. en-copyright= kn-copyright= en-aut-name=FukayaYuri en-aut-sei=Fukaya en-aut-mei=Yuri kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MaedaKazuki en-aut-sei=Maeda en-aut-mei=Kazuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YadaKeiji en-aut-sei=Yada en-aut-mei=Keiji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=CayaoJorge en-aut-sei=Cayao en-aut-mei=Jorge kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=TanakaYukio en-aut-sei=Tanaka en-aut-mei=Yukio kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=LuBo en-aut-sei=Lu en-aut-mei=Bo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Faculty of Environmental Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Department of Applied Physics, Nagoya University kn-affil= affil-num=3 en-affil=Department of Applied Physics, Nagoya University kn-affil= affil-num=4 en-affil=Department of Physics and Astronomy, Uppsala University kn-affil= affil-num=5 en-affil=Department of Applied Physics, Nagoya University kn-affil= affil-num=6 en-affil=Center for Joint Quantum Studies, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, Tianjin University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=110 cd-vols= no-issue=9 article-no= start-page=094420 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240911 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Ferrimagnetic structure in the high-pressure phase of ??Mn en-subtitle= kn-subtitle= en-abstract= kn-abstract=The ??Mn phase exhibits a large anomalous Hall effect (AHE) in its pressure-induced weak ferromagnetic (WFM) state, despite its relatively small spontaneous magnetization of ?0.02?B/Mn. To understand the underlying mechanism behind this AHE, we performed single crystal neutron diffraction measurements at 2.0 GPa to determine the magnetic structure of the WFM phase. Our investigation reveals a ferrimagnetic structure characterized by nearly collinear magnetic moments aligned along the [001] direction at sites I, II, III-1, and IV-1. In contrast, the small moments at sites III-2 and IV-2 lie within the (001) plane. The calculated net magnetization of this magnetic structure, (?0.08}0.10)??B/Mn atom, is in agreement with the experimentally determined spontaneous magnetization. The observation of a magnetic reflection at ?=(0,0,0) satisfies a key condition for the emergence of the AHE. en-copyright= kn-copyright= en-aut-name=ArakiShingo en-aut-sei=Araki en-aut-mei=Shingo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IwamotoKaisei en-aut-sei=Iwamoto en-aut-mei=Kaisei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=AkibaKazuto en-aut-sei=Akiba en-aut-mei=Kazuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KobayashiTatsuo C. en-aut-sei=Kobayashi en-aut-mei=Tatsuo C. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MunakataKoji en-aut-sei=Munakata en-aut-mei=Koji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=KanekoKoji en-aut-sei=Kaneko en-aut-mei=Koji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=OsakabeToyotaka en-aut-sei=Osakabe en-aut-mei=Toyotaka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= affil-num=1 en-affil=Department of Physics, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Department of Physics, Okayama University kn-affil= affil-num=4 en-affil=Department of Physics, Okayama University kn-affil= affil-num=5 en-affil=Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society kn-affil= affil-num=6 en-affil=Materials Sciences Research Center, Japan Atomic Energy Agency kn-affil= affil-num=7 en-affil=Materials Sciences Research Center, Japan Atomic Energy Agency kn-affil= END start-ver=1.4 cd-journal=joma no-vol=109 cd-vols= no-issue=17 article-no= start-page=174503 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240502 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Time-dependent Ginzburg-Landau theory of the vortex spin Hall effect en-subtitle= kn-subtitle= en-abstract= kn-abstract=We develop a time-dependent Ginzburg-Landau theory of the vortex spin Hall effect, i.e., a spin Hall effect that is driven by the motion of superconducting vortices. For the direct vortex spin Hall effect in which an input charge current drives the transverse spin current accompanying the vortex motion, we start from the well-known Schmid-Caroli-Maki solution for the time-dependent Ginzburg-Landau equation under the applied electric field, and find out the expression of the induced spin current. For the inverse vortex spin Hall effect in which an input spin current drives the longitudinal vortex motion and produces the transverse charge current, we microscopically construct the time-dependent Ginzburg-Landau equation under the applied spin accumulation gradient, and calculate the induced transverse charge current as well as the open circuit voltage. The time-dependent Ginzburg-Landau equation and its analytical solution developed here can be a basis for more quantitative numerical simulations of the vortex spin Hall effect. en-copyright= kn-copyright= en-aut-name=AdachiHiroto en-aut-sei=Adachi en-aut-mei=Hiroto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KatoYusuke en-aut-sei=Kato en-aut-mei=Yusuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OheJun-ichiro en-aut-sei=Ohe en-aut-mei=Jun-ichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=IchiokaMasanori en-aut-sei=Ichioka en-aut-mei=Masanori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Department of Basic Science, University of Tokyo kn-affil= affil-num=3 en-affil=Department of Physics, Toho University kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=109 cd-vols= no-issue=20 article-no= start-page=L201103 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240503 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Realization of nodal-ring semimetal in pressurized black phosphorus en-subtitle= kn-subtitle= en-abstract= kn-abstract=Topological semimetals are intriguing targets for exploring unconventional physical properties of massless fermions. Among them, nodal-line or nodal-ring semimetals have attracted attention for their unique one-dimensional band contact in momentum space and resulting nontrivial quantum phenomena. By field angular resolved magnetotransport measurements and theoretical calculations, we show that pressurized black phosphorus (BP) is an ideal nodal-ring semimetal with weak spin-orbit coupling, which has a sole and carrier density-tunable nodal ring isolated from other trivial bands. We also revealed that the large magnetoresistance effect and its field-angular dependence in semimetallic BP are due to highly anisotropic relaxation time. Our results establish pressurized BP as an elemental model material for exploring nontrivial quantum properties unique to the topological nodal ring. en-copyright= kn-copyright= en-aut-name=AkibaKazuto en-aut-sei=Akiba en-aut-mei=Kazuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=AkahamaYuichi en-aut-sei=Akahama en-aut-mei=Yuichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TokunagaMasashi en-aut-sei=Tokunaga en-aut-mei=Masashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KobayashiTatsuo C. en-aut-sei=Kobayashi en-aut-mei=Tatsuo C. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Science, University of Hyogo kn-affil= affil-num=3 en-affil=The Institute for Solid State Physics, The University of Tokyo kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=6 cd-vols= no-issue=1 article-no= start-page=013005 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240103 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Periodic superradiance in an Er:YSO crystal en-subtitle= kn-subtitle= en-abstract= kn-abstract=We observed periodic optical pulses from an Er:YSO crystal during irradiating with a continuous-wave excitation laser. We refer to this phenomenon as "periodic superradiance." This periodicity can be understood qualitatively by a simple model, in which a cyclic process of a continuous supply of population inversion and a sudden burst of superradiance is repeated. The excitation power dependences of peak interval and the pulse area can be interpreted with our simple model. In addition, the linewidth of superradiance is much narrower than an inhomogeneous broadening in a crystal. This result suggests that only Er3+ ions in a specific environment are involved in superradiance. en-copyright= kn-copyright= en-aut-name=HaraHideaki en-aut-sei=Hara en-aut-mei=Hideaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HanJunseok en-aut-sei=Han en-aut-mei=Junseok kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=ImaiYasutaka en-aut-sei=Imai en-aut-mei=Yasutaka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SasaoNoboru en-aut-sei=Sasao en-aut-mei=Noboru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YoshimiAkihiro en-aut-sei=Yoshimi en-aut-mei=Akihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=YoshimuraKoji en-aut-sei=Yoshimura en-aut-mei=Koji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=YoshimuraMotohiko en-aut-sei=Yoshimura en-aut-mei=Motohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=MiyamotoYuki en-aut-sei=Miyamoto en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=3 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=5 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=6 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=7 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=8 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=105 cd-vols= no-issue=10 article-no= start-page=103522 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20220517 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Axion cosmology in the presence of nontrivial Nambu-Goldstone modes en-subtitle= kn-subtitle= en-abstract= kn-abstract=Axion cosmology is reexamined taking into account the effect of kinetic pseudo-NambuGoldstone modes. When Peccei-Quinn (PQ) symmetry is broken by a chiral U(1) singlet, we find that the effect of the kinetic Nambu-Goldstone mode makes the axion dark matter untenable. When PQ symmetry is extended and is broken by two singlets, we find that axion cosmology works, but there are several differences from the axion cosmology studied in the literature. The differences are (1) an ordinary type of dark matter scaling of 1/cosmic scale factor(3) arising from a modulus field and not from the usual angular field, (2) the mass of the dark matter quantum in the ultralight range (10(-32)-10(-14)) eV, (3) the emergence of dark energy with a present density of order (a few meV)(4), consistent with observations, (4) the presence of a long-range spin-dependent force, and (5) slow-roll inflation after PQ symmetry breaking when conformal coupling to gravity is introduced. en-copyright= kn-copyright= en-aut-name=YoshimuraM. en-aut-sei=Yoshimura en-aut-mei=M. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= affil-num=1 en-affil= kn-affil= END start-ver=1.4 cd-journal=joma no-vol=107 cd-vols= no-issue=24 article-no= start-page=245117 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=20230609 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Phonon-mediated superconductivity in the Sb square-net compound LaCuSb2 en-subtitle= kn-subtitle= en-abstract= kn-abstract=We investigated the electronic structure and superconducting properties of single-crystalline LaCuSb2. The resistivity, magnetization, and specific heat measurements showed that LaCuSb2 is a bulk superconductor. The observed Shubnikov?de Haas oscillation and magnetic field dependence of the Hall resistivity can be reasonably understood assuming a slightly hole-doped Fermi surface. An electron-phonon coupling calculation clarified the difference from the isostructural compound LaAgSb2, indicating that (i) low-frequency vibration modes related to the interstitial layer sandwiched between the Sb square nets significantly contribute to the superconductivity and (ii) carriers with sizable electron-phonon coupling distribute isotropically on the Fermi surface. These are assumed to be the origin of the higher superconducting transition temperature compared with LaAgSb2. We conclude that the superconducting properties of LaCuSb2 can be understood within the framework of the conventional phonon-mediated mechanism. en-copyright= kn-copyright= en-aut-name=AkibaKazuto en-aut-sei=Akiba en-aut-mei=Kazuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KobayashiTatsuo C. en-aut-sei=Kobayashi en-aut-mei=Tatsuo C. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=107 cd-vols= no-issue=15 article-no= start-page=155142 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=20230425 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Ginzburg-Landau action and polarization current in an excitonic insulator model of electronic ferroelectricity en-subtitle= kn-subtitle= en-abstract= kn-abstract=In comparison to transport of spin polarization in ferromagnets, transport of electric polarization in ferroelectrics remains less explored. Taking an excitonic insulator model of electronic ferroelectricity as a prototypical example, we theoretically investigate the low-energy dynamics and transport of electric polarization by microscopically constructing the Ginzburg-Landau action. We show that, because of the scalar nature of the excitonic order parameter, only the longitudinal fluctuations are relevant to the transport of electric polarization. We also formulate the electric-polarization diffusion equation, in which the electric-polarization current is defined purely electronically without recourse to the lattice degrees of freedom. en-copyright= kn-copyright= en-aut-name=AdachiHiroto en-aut-sei=Adachi en-aut-mei=Hiroto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IkedaNaoshi en-aut-sei=Ikeda en-aut-mei=Naoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=SaitohEiji en-aut-sei=Saitoh en-aut-mei=Eiji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Department of Physics, Okayama University kn-affil= affil-num=3 en-affil=Department of Applied Physics, The University of Tokyo kn-affil= END start-ver=1.4 cd-journal=joma no-vol=107 cd-vols= no-issue=4 article-no= start-page=043114 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=20230413 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Measurement of Doppler effects in a cryogenic buffer-gas cell en-subtitle= kn-subtitle= en-abstract= kn-abstract=Buffer-gas cooling is a universal cooling technique for molecules and used for various purposes. One of its ap- plications is using molecules inside a buffer-gas cell for low-temperature spectroscopy. Although a high-intensity signal is expected in the cell, complex molecular dynamics is a drawback for precise spectroscopy. In this study, we performed high-resolution absorption spectroscopy of low -J transitions in the òƒ®(0, 0, 0)-?X²ƒ°+(0, 0, 0) band of calcium monohydroxide (CaOH). CaOH molecules were produced by laser ablation in a copper cell and cooled to ?5 K using helium buffer gas. We probed the Doppler effects in a buffer-gas cell by injecting counterpropagating lasers inside the cell. The time evolutions of the Doppler width and shift were simulated using a dedicated Monte Carlo simulation and compared with data. en-copyright= kn-copyright= en-aut-name=HiramotoAyami en-aut-sei=Hiramoto en-aut-mei=Ayami kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=BabaMasaaki en-aut-sei=Baba en-aut-mei=Masaaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=EnomotoKatsunari en-aut-sei=Enomoto en-aut-mei=Katsunari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=IwakuniKana en-aut-sei=Iwakuni en-aut-mei=Kana kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KumaSusumu en-aut-sei=Kuma en-aut-mei=Susumu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=TakahashiYuiki en-aut-sei=Takahashi en-aut-mei=Yuiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=TobaruReo en-aut-sei=Tobaru en-aut-mei=Reo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=MiyamotoYuki en-aut-sei=Miyamoto en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Department of Chemistry, Graduate School of Science, Kyoto University kn-affil= affil-num=3 en-affil=Department of Physics, University of Toyama kn-affil= affil-num=4 en-affil=Institute for Laser Science, University of Electro-Communications kn-affil= affil-num=5 en-affil=Atomic, Molecular and Optical Physics Laboratory, RIKEN kn-affil= affil-num=6 en-affil=Division of Physics, Mathematics, and Astronomy, California Institute of Technology kn-affil= affil-num=7 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=8 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=106 cd-vols= no-issue=16 article-no= start-page=L161113 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20221027 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Observation of superconductivity and its enhancement at the charge density wave critical point in LaAgSb 2 en-subtitle= kn-subtitle= en-abstract= kn-abstract=We discover superconductivity (SC) in LaAgSb2 at ambient pressure and its close correlation with a charge density wave (CDW) under pressure. The superconducting transition temperature (Tc) exhibits a sharp peak at a CDW critical pressure of 3.2 GPa. We demonstrate that the carriers inhabiting the Sb-square net are crucial not only in the formation of CDW but also in SC for their relatively strong electron-phonon coupling (EPC). Furthermore, theoretical EPC strength in pristine LaAgSb 2 cannot explain the observed peak with Tc?1 K, which indicates that an additional mechanism reinforces SC only around the CDW critical pressure. en-copyright= kn-copyright= en-aut-name=AkibaKazuto en-aut-sei=Akiba en-aut-mei=Kazuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=UmeshitaNobuaki en-aut-sei=Umeshita en-aut-mei=Nobuaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KobayashiTatsuo C. en-aut-sei=Kobayashi en-aut-mei=Tatsuo C. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=105 cd-vols= no-issue=4 article-no= start-page=045316 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=2022425 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Lattice Boltzmann model for capillary interactions between particles at a liquid-vapor interface under gravity en-subtitle= kn-subtitle= en-abstract= kn-abstract=A computational technique based on the lattice Boltzmann method (LBM) is developed to simulate the wettable particles adsorbed to a liquid-vapor interface under gravity. The proposed technique combines the improved smoothed-profile LBM for the treatment of moving solid particles in a fluid and the free-energy LBM for the description of a liquid-vapor system. Five benchmark two-dimensional problems are examined: (A) a stationary liquid drop in the vapor phase; a wettable particle adsorbed to a liquid-vapor interface in (B) the absence and (C) the presence of gravity; (D) two freely moving particles at a liquid-vapor interface in the presence of gravity (i.e., capillary flotation forces); and (E) two vertically constrained particles at a liquid-vapor interface (i.e., capillary immersion forces). The simulation results are in good quantitative agreement with theoretical estimations, demonstrating that the proposed technique can reproduce the capillary interactions between wettable particles at a liquid-vapor interface under gravity. en-copyright= kn-copyright= en-aut-name=MinoYasushi en-aut-sei=Mino en-aut-mei=Yasushi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TanakaHazuki en-aut-sei=Tanaka en-aut-mei=Hazuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NakasoKoichi en-aut-sei=Nakaso en-aut-mei=Koichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=GotohKuniaki en-aut-sei=Gotoh en-aut-mei=Kuniaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=ShintoHiroyuki en-aut-sei=Shinto en-aut-mei=Hiroyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Department of Chemical Engineering, Fukuoka University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=105 cd-vols= no-issue=10 article-no= start-page=104417-1 end-page=104417-14 dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=2022315 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Antiferromagnetic spin Seebeck effect across the spin-flop transition: A stochastic Ginzburg-Landau simulation en-subtitle= kn-subtitle= en-abstract= kn-abstract=We investigate the antiferromagnetic spin Seebeck effect across the spin-flop transition in a numerical simulation based on the time-dependent Ginzburg-Landau equation for a bilayer of a uniaxial insulating antiferromagnet and an adjacent metal. By directly simulating the rate of change of the conduction-electron spin density s in the adjacent metal layer, we demonstrate that a sign reversal of the antiferromagnetic spin Seebeck effect across the spin-flop transition occurs when the interfacial coupling of s to the staggered magnetization n of the antiferromagnet dominates, whereas no sign reversal appears when the interfacial coupling of s to the magnetization m dominates. Moreover, we show that the sign reversal is influenced by the degree of spin dephasing in the metal layer. Our result indicates that the sign reversal is not a generic property of a simple uniaxial antiferromagnet, but controlled by microscopic details of the exchange coupling at the interface and the spin dephasing in the metal layer. en-copyright= kn-copyright= en-aut-name=YamamotoYutaka en-aut-sei=Yamamoto en-aut-mei=Yutaka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IchiokaMasanori en-aut-sei=Ichioka en-aut-mei=Masanori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=AdachiHiroto en-aut-sei=Adachi en-aut-mei=Hiroto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Department of Physics, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=3 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=105 cd-vols= no-issue=3 article-no= start-page=035108 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=202216 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Magnetotransport studies of the Sb square-net compound LaAgSb2 under high pressure and rotating magnetic fields en-subtitle= kn-subtitle= en-abstract= kn-abstract=Square-net-layered materials have attracted attention as an extended research platform of Dirac fermions and of exotic magnetotransport phenomena. In this study, we investigated the magnetotransport properties of LaAgSb2, which has Sb-square-net layers and shows charge density wave (CDW) transitions at ambient pressure. The application of pressure suppresses the CDWs, and above a pressure of 3.2 GPa a normal metallic phase with no CDWs is realized. By utilizing a mechanical rotator combined with a high-pressure cell, we observed the angular dependence of the Shubnikov?de Haas (SdH) oscillation up to 3.5 GPa, and we confirmed the notable two-dimensional nature of the Fermi surface. In the normal metallic phase, we also observed a remarkable field-angular-dependent magnetoresistance (MR), which exhibited a gbutterflylikeh polar pattern. To understand these results, we theoretically calculated the Fermi surface and conductivity tensor at the normal metallic phase. We showed that the SdH frequency and Hall coefficient calculated based on the present Fermi surface model agree well with the experiment. The transport properties in the normal metallic phase are mostly dominated by the anisotropic Dirac band, which has the highest conductivity due to linear energy dispersions.We also proposed that momentum-dependent relaxation time plays an important role in the large transverse MR and negative longitudinal MR in the normal metallic phase, which is experimentally supported by the considerable violation of Kohlerfs scaling rule. Although quantitatively complete reproduction was not achieved, the calculation showed that the elemental features of the butterfly MR could be reasonably explained as the geometrical effect of the Fermi surface. en-copyright= kn-copyright= en-aut-name=AkibaKazuto en-aut-sei=Akiba en-aut-mei=Kazuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=UmeshitaNobuaki en-aut-sei=Umeshita en-aut-mei=Nobuaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KobayashiTatsuo C. en-aut-sei=Kobayashi en-aut-mei=Tatsuo C. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=104 cd-vols= no-issue=14 article-no= start-page=L140402 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=2021107 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Spin-gap formation due to spin-Peierls instability in ƒÎ-orbital-ordered NaO2 en-subtitle= kn-subtitle= en-abstract= kn-abstract=We have investigated the low-temperature magnetism of sodium superoxide (NaO2), in which spin, orbital, and lattice degrees of freedom are closely entangled. The magnetic susceptibility shows anomalies at T1 = 220 K and T2 = 190 K, which correspond well to the structural phase transition temperatures, and a sudden decrease below T3 = 34 K. At 4.2 K, the magnetization shows a clear stepwise anomaly around 30 T with a large hysteresis. In addition, the muon spin relaxation experiments indicate no magnetic phase transition down to T = 0.3 K. The inelastic neutron scattering spectrum exhibits magnetic excitation with a finite energy gap. These results confirm that the ground state of NaO2 is a spin-singlet state. To understand this ground state in NaO2, we performed Raman scattering experiments. All the Raman-active libration modes expected for the marcasite phase below T2 are observed. Furthermore, we find that several new peaks appear below T3. This directly evidences the low crystal symmetry, namely, the presence of the phase transition at T3.We conclude that the singlet ground state of NaO2 is due to the spin-Peierls instability. en-copyright= kn-copyright= en-aut-name=MiyajimaMizuki en-aut-sei=Miyajima en-aut-mei=Mizuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=AstutiFahmi en-aut-sei=Astuti en-aut-mei=Fahmi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=FukudaTakahito en-aut-sei=Fukuda en-aut-mei=Takahito kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KodaniMasashi en-aut-sei=Kodani en-aut-mei=Masashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=IidaShinsuke en-aut-sei=Iida en-aut-mei=Shinsuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=AsaiShinichiro en-aut-sei=Asai en-aut-mei=Shinichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=MatsuoAkira en-aut-sei=Matsuo en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=MasudaTakatsugu en-aut-sei=Masuda en-aut-mei=Takatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=KindoKoichi en-aut-sei=Kindo en-aut-mei=Koichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=HasegawaTakumi en-aut-sei=Hasegawa en-aut-mei=Takumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=KobayashiTatsuo C. en-aut-sei=Kobayashi en-aut-mei=Tatsuo C. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=NakanoTakehito en-aut-sei=Nakano en-aut-mei=Takehito kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=WatanabeIsao en-aut-sei=Watanabe en-aut-mei=Isao kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=KambeTakashi en-aut-sei=Kambe en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= affil-num=1 en-affil=Department of Physics, Okayama University kn-affil= affil-num=2 en-affil=Advanced Meson Science Laboratory, RIKEN Nishina Center kn-affil= affil-num=3 en-affil=Department of Physics, Okayama University kn-affil= affil-num=4 en-affil=Department of Physics, Okayama University kn-affil= affil-num=5 en-affil=Institute for Solid State Physics, University of Tokyo kn-affil= affil-num=6 en-affil=Institute for Solid State Physics, University of Tokyo kn-affil= affil-num=7 en-affil=Institute for Solid State Physics, University of Tokyo kn-affil= affil-num=8 en-affil=Institute for Solid State Physics, University of Tokyo kn-affil= affil-num=9 en-affil=Institute for Solid State Physics, University of Tokyo kn-affil= affil-num=10 en-affil=Graduate School of Advanced Science and Engineering, Hiroshima University kn-affil= affil-num=11 en-affil=Department of Physics, Okayama University kn-affil= affil-num=12 en-affil=Institute of Quantum Beam Science, Ibaraki University kn-affil= affil-num=13 en-affil=Advanced Meson Science Laboratory, RIKEN Nishina Center kn-affil= affil-num=14 en-affil=Department of Physics, Okayama University kn-affil= END