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Fases topológicas impulsadas por la correlación en grafeno de doble capa retorcida de ángulo mágico
Youngjoon Choi1,2,3, Hyunjin Kim1,2,3, Yang Peng4
1T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA, USA.
Nature
|January 19, 2021
Resumen
El grafeno de doble capa retorcida de ángulo mágico revela seis nuevas fases topológicas impulsadas por fuertes interacciones electrónicas. Estas fases, mapeadas con microscopía de túnel de barrido, surgen de la ruptura de simetría inducida por la correlación en un campo magnético.
Área de la Ciencia:
- Física de la materia condensada
- Ciencias de los materiales
- Los materiales cuánticos
Sus antecedentes:
- El grafeno de doble capa retorcido de ángulo mágico (MATBG) muestra fenómenos correlacionados debido a fuertes interacciones electrón-electrón.
- Estas interacciones causan la reconstrucción de la superficie de Fermi y la formación de varias fases correlacionadas.
- Las propiedades microscópicas y topológicas locales de muchas fases de MATBG siguen siendo indeterminadas.
Objetivo del estudio:
- Para mapear las fases topológicas en MATBG bajo un campo magnético finito.
- Determinar las propiedades microscópicas locales y el carácter topológico de las fases emergentes.
- Investigar la influencia de las interacciones electrónicas en la estructura de la banda MATBG.
Principales métodos:
- Se utilizó el microscopio de túnel de barrido (STM) para sondear el MATBG.
- Mapeó la densidad local de los estados a nivel de Fermi.
- Creó un diagrama de ventilador local de Landau variando el dopaje electrostático y el campo magnético.
Principales resultados:
- Descubrió seis fases topológicas distintas que surgen de rellenos enteros en campos magnéticos finitos.
- Identificó que estas fases se originan en transiciones de ruptura de simetría impulsadas por la correlación.
- Se observaron modificaciones significativas en el espectro de Landau de neutralidad de carga, incluida la asimetría de agujero de electrones y la gran división del nivel cero de Landau.
Conclusiones:
- Las interacciones electrónicas fuertes alteran fundamentalmente la estructura de la banda MATBG.
- Estas interacciones permiten la formación de nuevas fases topológicas impulsadas por la correlación.
- Los hallazgos proporcionan información sobre la compleja interacción de las correlaciones, la topología y el magnetismo en los materiales 2D.
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