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調節可能な相関チェーン分離器とモアール超網の鉄磁性

Guorui Chen^1,2, Aaron L Sharpe^3,4, Eli J Fox^4,5

¹Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

|March 6, 2020

まとめ

研究者らは,ABC三層グラフェン/hBNモエール超格子で相関するチェーン絶縁剤を観察した. このトポロジカル状態はフェロマグネティズムと量子化されたホール抵抗を示し,新しいトポロジカル材料への道を開く.

科学分野:

凝縮物質物理学
材料科学
量子現象について

背景:

2D電子系における量子ホール効果は,有限なチェーン数とキラル・エッジ状態によって特徴づけられるトポロジック状態である.
外部磁場なしの整数量子ホール効果を示すチェーン分離器は,理論的には格子モデルで提案された.
ABC三層グラフェン/六角性ボロン窒化物 (ABC-TLG/hBN) のモエール超網は,平らで,トポロジ的に非平凡なミニバンドがあるため,チェーンの断絶体を探索するための調整可能なプラットフォームを提供します.

研究の目的:

ABC-TLG/hBNモアール超網で相関するチェーン分離器を実験的に観察し,特徴づけること.
モーレのミニバンドで,電場によるチェーン数の調節性を調査する.
観測されたトポロジカル状態の磁気および輸送特性を探求する.

主な方法:

ABC-TLG/hBNモアール超網の製造
磁場と電界の変動による電気伝送測定
ハール抵抗の定量化と磁気ヒステリシスの分析

主要な成果:

ABC-TLG/hBNシステムにおける相関するチェーン分離器の観測.
垂直電場を反転させることで,電気的に調節可能なチェーン数を示す.
h/2e^2の量子化ハール抵抗 (C=2) のトポロジックホールのミニバンドは,四分の一の充填と磁場> 0.4 Tで.
フェロマグネティズム,磁気ヒステリシス,およびゼロフィールド異常ホール信号の観測.

結論:

ゼロ磁場でのABC-TLG/hBNモエール超グリットのC=2チェーン分離器の実験的実現
この発見は,新しいトポロジック状態の探査のためのモアールシステムの可能性を強調しています.
平らで,トポロジ的に非平凡なバンドでユニークな刺激を持つ相関したトポロジカル状態を発見するための道を開きます.

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