時間逆対称条件下における非線形ホール効果の観測
Qiong Ma1, Su-Yang Xu1, Huitao Shen1
1Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nature
|December 19, 2018
まとめ
研究者は磁場のない非磁性WTe2バイレイヤで非線形ホール効果を観察した. この新しい効果は,異常なホール効果とは異なり,量子材料のベリー曲線を検出する新しい方法を提供します.
科学分野:
- 凝縮物質物理学
- 量子材料科学
- 電気輸送現象
背景:
- トポロジカル・インヴァリアントの発見に不可欠なホール効果は,典型的には磁場を必要とします.
- 異常なホール効果は,外場のない磁気材料で発生します.
- 時間の反転対称性は,通常,磁場ゼロの下の非磁気材料におけるホール効果を防ぐ.
研究 の 目的:
- 時間逆対称条件下における非磁性物質における非線形ホール効果を調査する.
- 量子材料の線形反応を超えた電気輸送現象を調査する.
- 非線形電流を用いたベリー曲線の検出のための新しい方法を実証する.
主な方法:
- 二層トングステンディテルリド (WTe2) の電気伝送の実験観察
- 電流の適用と横方向と縦方向の電圧の測定
- 非線形応答体制における電流-電圧特性の分析.
主要な成果:
- 磁場なしでも2層のWTe2で非線形ホール電圧を観測した.
- 異常なホール効果の線形特性とは異なり,二次的な電流-電圧関係を示した.
- 大きな横断電圧反応を測定し その結果は 90度近くの非線形ホール角度です
- 非線形ホール効果をベリー曲率二極モメントの直接プローブとして示した.
結論:
- 非線形ホール効果は,非磁気量子材料 (WTe2) で時間逆対称性で実証されている.
- この効果は,二次的なI-V特性を含む異常なホール効果と比較して異なる特性を示しています.
- 非線形ホール効果は,材料のベリー曲線を検出するための新しい敏感な方法を提供します.
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