Experimental study for magnetic transport properties in the nonsymmorphic magnets

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03445
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Osaka University
• Principal Investigator: Murakawa Hiroshi 大阪大学, 大学院理学研究科, 助教 (40611744)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 巨大磁気抵抗効果 / 磁気ポーラロン / 異方的磁気抵抗効果 / 少数キャリア系半導体 / 層状磁性半導体

Outline of Final Research Achievements

We found that the layered magnetic semiconductor CeTe1.83Sb0.17 exhibits the giant anisotropic magnetoresistance. The electrical resistivity decreases nearly four orders of magnitude in 0.4 T along [100] at 2 K, accompanied by the transition from the antiferromagnetic state to the forced-ferromagnetic state.In contrast, the change of the electrical resistivity is very small in a magnetic field normal to [001].
We prepared the single crystals of CeTe2-xSbx with various carrier density by changing the composition ratio x and compared the magnitude of the magnetoresistance. We observed that the samples with the low carrier density (< 10^18 cm-3) show the large magnetoresistance exceeding two digits. The electrical resistivity approaches a constant value when the magnetization gets close to saturation. In contrast, the change is very tiny in the sample with much higher density. We consider that the giant negative magnetoresistance originates from the mobility change of magnetic polarons.

Free Research Field

物性物理学

Academic Significance and Societal Importance of the Research Achievements

磁場中で物質の電気抵抗率が著しく変化する巨大磁気抵抗効果を示す物質は数多く知られているが、磁場方向に依存して何桁も変化する巨大な異方性を示す物質はこれまでにほとんど知られていなかった。本研究では層状構造のCe化合物半導体の電気抵抗率が、ヘリウム温度領域において、永久磁石で到達可能な0.4テスラの磁場方向に依存して4桁程度変化することを発見した。今回観測した前例のない規模での異方性磁気抵抗効果は、希薄な電子密度の磁性半導体で実現する新たな現象であり、その電子状態を理解することにより磁場方向に非常に敏感な検出器等への応用が期待させる。