グラフェン超格子における分数フラクタル量子ホール効果の証拠
Lei Wang1, Yuanda Gao2, Bo Wen3
1Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA. Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA.
Science (New York, N.Y.)
|January 20, 2016
まとめ
研究者は,グラフェン超網でホフスタッターのエネルギースペクトルを探索し,新しい分数量子ホール効果状態を観察しました. これらの発見は,現在の理論的理解を超えた新しい多体状態を明らかにします.
科学分野:
- 凝縮物質物理学
- 量子ホール効果
- トポロジカル・オーダー
背景:
- ホフスタッターのスペクトルは,強烈に相互作用するシステムで調節可能なトポロジカル・オーダーを提供します.
- 以前の実験は低ブロッヒ帯の埋着に限定され,探査を制限していました.
- 複雑な量子現象を研究するためのプラットフォームを 提供しています
研究 の 目的:
- 高移動性のグラフェン超網でホフスタッターのエネルギースペクトル全体を調査する.
- トポロジカル・オーダーと ホール・エフェクトを研究する.
- 新しい多体状態を特定し特徴づけること.
主な方法:
- 高移動性のグラフェン超網の製造
- 量子ホール効果現象の測定
- 様々な磁場と埋着におけるホフスタッターのエネルギースペクトルの分析.
主要な成果:
- フラクタルホフスタッタースペクトルに関連した従来の分数量子ホール効果 (QHE) 状態と整数QHE状態の共存が観察された.
- 大きい磁場の下の ブロック充填指数で新しい一連の状態を検出した.
- これらの新しい状態は 現在の理論的モデルでは説明できません
結論:
- 完全なホフスタッターのスペクトルは,グラフェン超網で実験的にアクセスできます.
- 新しい分数ブロック帯の量子ホール効果状態は,異なる種類の多体状態を示します.
- これらの発見は,既存の理論的枠組みに挑戦し,トポロジック物質の研究のための新しい道を開きます.
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