Hideki Aoshima, Iduru Shigeta, Akiko Nomura, Kunio Yubuta, Touru Yamauchi, Rie Y. Umetsu, Takeshi Kanomata, Masahiko Hiroi . The critical behavior of magnetization near the Curie temperature i2024 · 担当区分： 責任著者 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： IEEE Transactions on Magnetics We present an analysis of the critical behavior of magnetization near the Curie temperature <italic>T</italic><sub>C</sub> in Heusler alloy Co<sub>2</sub>TiGa<sub>0.3</sub>Sn<sub>0.7</sub>, which is a promising candidate for highly spin-polarized materials that exhibit the characteristic properties of magnetic Weyl states. Weyl semimetals have garnered significant interest for their potential applications in spintronics devices, owing to their anomalous magnetoelectronic and magnetothermal properties. The magnetization of the synthesized Heusler alloy Co<sub>2</sub>TiGa<sub>0.3</sub>Sn<sub>0.7</sub> was investigated in the vicinity of <italic>T</italic><sub>C</sub>. The analysis of magnetic isotherms for Co<sub>2</sub>TiGa<sub>0.3</sub>Sn<sub>0.7</sub> reveals that the critical exponent δ is deduced to be 5.16 in the high field region and 4.96 in the low field region. The obtained value of δ deviates from the value of 3.0 expected by the conventional molecular field theory. However, it is in close agreement with the value of 5.0 predicted by the spin fluctuation theory for weak itinerant electron ferromagnets, exhibiting that the spin fluctuation theory is applicable even to highly spin-polarized Heusler alloys. DOI： 10.1109/TMAG.2024.3414430 Scopus researchmap
T. Kanomata, Y. Amako, Y. Ida, Y. Adachi, T. Osaki, T. Eto, H. Nishihara, I. Shigeta, S. Imada, M. Doi . Magnetic properties of ferromagnetic Heusler alloy Co2ZrSn .2022 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） The results of experimental investigations of the crystal structure, permeability, magnetization and Mössbauer spectroscopy of Co2ZrSn are reported. The sample, which was prepared by arc melting, comprised of a Heusler structure Co2ZrSn that coexisted with a small amount of an impurity phase. The Curie temperature TC of Co2ZrSn was found to be 452.3 K. At 1.8 K the magnetic moment of Co2ZrSn was estimated to be 2.0 μB/f.u., confirming that the magnetic moment of Co2ZrSn obeys the Slater-Pauling rule. The temperature variation of the spontaneous magnetization Ms roughly follows the Brillouin function for spin value S = 1/2. However, in the temperature region of T/TC > 0.6, Ms is distinctly higher than the Brillouin function. The TC of Co2ZrSn was almost independent of pressure. The Mössbauer spectroscopy measurements showed that the isomer shift I.S. (1.5 mm/s at 295 K) was approximately temperature independent. At 95 K the value of the hyperfine magnetic field HhfSn at the Sn nuclei was found to be 101 kOe. The temperature variation of HhfSn of Co2ZrSn roughly followed the Brillouin function for S = 1/2. On the basis of the experimental results, the electronic and magnetic properties of Co2ZrSn are discussed. DOI： 10.1016/j.jpcs.2022.110635 Scopus researchmap
Takaaki Yokoyama, Iduru Shigeta, Akiko Nomura, Kunio Yubuta, Touru Yamauchi, Rie Y. Umetsu, Hironori Nishihara, Takeshi Kanomata, Masahiko Hiroi . Critical Behavior of the Magnetization2021 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） We report the critical behavior of the magnetization in Heusler alloy Co2TiGa0.8Sn0.2 as a potential candidate of high spin polarized materials with the characteristics of topological Weyl fermions. The Weyl semimetals are materials of great interest for applying spintronics devices, due to their unusual magnetoelectronic and magnetothermal properties. The magnetic properties of the synthesized Heusler alloy Co2TiGa0.8Sn0.2 are investigated around the Curie temperature TC. The magnetic isotherm measurements of Co2TiGa0.8Sn0.2 around TC exhibit that the critical exponent δ is deduced to be 4.455(4) in high maximum applied field of 50 kOe and 4.823(9) in low maximum applied field of 10 kOe, respectively. Both δ values are different from 3.0 derived by the conventional molecular field theory, but they are close to 5.0 predicted by the spin fluctuation theory for the itinerant electron ferromagnets. Possible origins for the discrepancy between experimental results and theoretical models are also discussed. DOI： 10.1109/TMAG.2021.3097164 Scopus researchmap
