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Imagen del flujo viscoso del fluido Dirac en el grafeno

Mark J H Ku^1,2,3,4, Tony X Zhou^1,5, Qing Li¹

¹Department of Physics, Harvard University, Cambridge, MA, USA.

|July 24, 2020

Resumen

Los investigadores fotografiaron directamente el flujo de electrones viscosos en el grafeno a temperatura ambiente, confirmando su comportamiento de fluido Dirac crítico cuántico. Este avance permite estudiar el transporte hidrodinámico en nuevos materiales cuánticos.

Área de la Ciencia:

Física de la materia condensada
Ciencia de los materiales cuánticos

Sus antecedentes:

Se predice que el plasma de agujero de electrones del grafeno, cerca de la neutralidad de carga, exhibirá un comportamiento crítico cuántico con transporte hidrodinámico universal.
Las mediciones anteriores de transporte eléctrico sugirieron flujo de electrones hidrodinámico, pero carecían de visualización directa en el punto de neutralidad de carga.
Una predicción clave es una viscosidad de corte cerca de las tasas mínimas de límite y dispersión en el tiempo de Planck.

Objetivo del estudio:

Imagen directa y demostración del flujo de fluido viscoso de Dirac en grafeno a temperatura ambiente.
Verificar experimentalmente la descripción hidrodinámica del transporte de electrones en el punto de neutralidad de carga.
Para medir la viscosidad y las tasas de dispersión y compararlas con las predicciones teóricas de la criticidad cuántica.

Principales métodos:

Utilizó imágenes magnéticas a nanoescala con centros de vacío de nitrógeno (NV) en diamante como magnetómetros cuánticos de espín.
Se utiliza la magnetometría de escaneo de un solo espín y de amplio campo para detectar el campo magnético extraviado generado por el flujo de electrones.
Imágenes combinadas con mediciones de transporte eléctrico para determinar las propiedades del fluido.

Principales resultados:

Se visualizó directamente un perfil de flujo de Poiseuille parabólico para el transporte de electrones en grafeno de alta movilidad cerca de la neutralidad de carga.
Este perfil es característico del flujo viscoso, en contraste con el flujo uniforme en conductores convencionales y grafeno de baja movilidad.
La viscosidad obtenida y las tasas de dispersión son consistentes con los valores teóricos para un fluido Dirac crítico cuántico casi ideal.

Conclusiones:

Se estableció evidencia experimental directa para el transporte de fluido viscoso de Dirac en grafeno a temperatura ambiente.
Los hallazgos validan la descripción hidrodinámica de los sistemas críticos cuánticos y proporcionan una plataforma para estudiar electrones fuertemente correlacionados.
Demostró la utilidad de los magnetómetros cuánticos de espín para sondear fenómenos electrónicos a nanoescala.

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