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Gran efecto Hall anómalo en un antiferromagnético no colineal a temperatura ambiente

Satoru Nakatsuji^1,2, Naoki Kiyohara¹, Tomoya Higo¹

¹Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan.

|November 3, 2015

Resumen

Los investigadores descubrieron un gran efecto Hall anómalo en el antimagnético Mn3Sn, incluso con una magnetización mínima. Este hallazgo abre posibilidades para los dispositivos espintrónicos, ofreciendo una nueva forma de controlar las propiedades electrónicas sin campos magnéticos fuertes.

Área de la Ciencia:

Física de la materia condensada
Ciencias de los materiales
La tecnología Spintronics

Sus antecedentes:

El efecto Hall anómalo (AHE) se observa típicamente en materiales ferromagnéticos y es proporcional a la magnetización.
Los antiferromagnetos generalmente no exhiben un AHE significativo en el campo magnético cero debido a su magnetización neta de desaparición.
Las teorías recientes sugieren que AHE puede ocurrir en antiferromagnetos y líquidos de espín a través de conceptos de fase de Berry, independientemente de la magnetización neta.

Objetivo del estudio:

Investigar la existencia y magnitud del efecto Hall anómalo en materiales antiferromagnéticos sin magnetización de espín neto.
Explorar el potencial de los antiferromagnetos para aplicaciones que requieren un efecto Hall significativo en ausencia de campos magnéticos fuertes.

Principales métodos:

Medición experimental de la conductividad de Hall en Mn3Sn, un antiferromagnético con una estructura de espín no collineal.
Caracterización de las propiedades magnéticas del Mn3Sn, incluido su momento ferromagnético débil.
Investigación de la respuesta dependiente del campo del efecto Hall anómalo en Mn3Sn.

Principales resultados:

Se observó una gran conductividad Hall anómala en Mn3Sn, alcanzando ~ 20 (Ω · cm) -1 a temperatura ambiente y > 100 (Ω · cm) -1 a bajas temperaturas.
La magnitud AHE observada es comparable a la encontrada en los metales ferromagnéticos.
El signo del efecto Hall podría cambiarse utilizando un pequeño campo magnético (cientos de oersted) debido al momento ferromagnético débil y suave del material.

Conclusiones:

Este estudio proporciona la primera evidencia empírica de un significativo efecto Hall anómalo de campo cero en un antiferromagnético.
El estado antiferromagnético quiral del Mn3Sn permite una AHE grande y conmutable, distinta de los mecanismos convencionales.
Los hallazgos sugieren aplicaciones potenciales en la espintrónica, particularmente para dispositivos de memoria de bajo campo de dispersión.

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