Faculty of Science

町田 洋

マチダ ヨウ  (Yo Machida)

基本情報

所属
学習院大学 理学部 教授
学位
博士(理学)

研究者番号
40514740
J-GLOBAL ID
200901036313769260
researchmap会員ID
6000012446

研究キーワード

 1

経歴

 3

論文

 34
  • Yo Machida, Valentina Martelli, Alexandre Jaoui, Benoît Fauqué, Kamran Behnia
    Fizyka Nyzkykh Temperatur 50(7) 638-648 2024年5月24日  査読有り
  • Yuna Nakajima, Yuichi Akahama, Yo Machida
    Physical Review Research 6(1) 013125 2024年1月31日  査読有り
  • Xiaokang Li, Yo Machida, Alaska Subedi, Zengwei Zhu, Liang Li, Kamran Behnia
    Nature Communications 14(1) 1027 2023年2月23日  査読有り
    Abstract The origin of phonon thermal Hall Effect (THE) observed in a variety of insulators is yet to be identified. Here, we report on the observation of a thermal Hall conductivity in a non-magnetic elemental insulator, with an amplitude exceeding what has been previously observed. In black phosphorus (BP), the longitudinal (κii), and the transverse, κij, thermal conductivities peak at the same temperature and at this peak temperature, the κijjj/B is ≈ 10−4−10−3 T−1. Both these features are shared by other insulators displaying THE, despite an absolute amplitude spreading over three orders of magnitude. The absence of correlation between the thermal Hall angle and the phonon mean-free-path imposes a severe constraint for theoretical scenarios of THE. We show that in BP a longitudinal and a transverse acoustic phonon mode anti-cross, facilitating wave-like transport across modes. The anisotropic charge distribution surrounding atomic bonds can pave the way for coupling between phonons and the magnetic field.
  • Taiki Uehara, Takumi Ohtsuki, Masafumi Udagawa, Satoru Nakatsuji, Yo Machida
    Nature Communications 13(1) 4604 2022年8月6日  査読有り
    Abstract It has become common knowledge that phonons can generate thermal Hall effect in a wide variety of materials, although the underlying mechanism is still controversial. We study longitudinal κxx and transverse κxy thermal conductivity in Pr2Ir2O7, which is a metallic analog of spin ice. Despite the presence of mobile charge carriers, we find that both κxx and κxy are dominated by phonons. A T/H scaling of κxx unambiguously reveals that longitudinal heat current is substantially impeded by resonant scattering of phonons on paramagnetic spins. Upon cooling, the resonant scattering is strongly affected by a development of spin ice correlation and κxx deviates from the scaling in an anisotropic way with respect to field directions. Strikingly, a set of the κxx and κxy data clearly shows that κxy correlates with κxx in its response to magnetic field including a success of the T/H scaling and its failure at low temperature. This remarkable correlation provides solid evidence that an indispensable role is played by spin-phonon scattering not only for hindering the longitudinal heat conduction, but also for generating the transverse response.
  • Takayuki Isono, Yo Machida, Wataru Fujita
    Journal of the Physical Society of Japan 89(7) 073707 2020年7月15日  査読有り

MISC

 3

書籍等出版物

 1

所属学協会

 1

共同研究・競争的資金等の研究課題

 9