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La supresión de la transición metal- aislante en el VO2 por la formación de vacíos de oxígeno inducidos por el campo
Jaewoo Jeong1, Nagaphani Aetukuri, Tanja Graf
1IBM Almaden Research Center, San Jose, CA 95120, USA.
Science (New York, N.Y.)
|March 23, 2013
Resumen
El acoplamiento líquido iónico del dióxido de vanadio (VO2) estabiliza su fase metálica hasta 5 Kelvin. Este efecto es causado por las vacantes de oxígeno, no por los portadores electrostáticos, lo que ofrece nuevos conocimientos sobre los mecanismos de bloqueo de electrolitos.
Área de la Ciencia:
- Física de la materia condensada Física de la materia condensada
- Ciencia de los materiales Ciencia de los materiales.
- La electroquímica es electroquímica.
Sus antecedentes:
- El encierro de electrolitos con líquidos iónicos es un método clave para ajustar las propiedades electrónicas de los aislantes correlacionados.
- El dióxido de vanadio (VO2) es un material correlacionado representativo que exhibe una transición de metal a aislante (MIT) cerca de la temperatura ambiente.
Objetivo del estudio:
- Para investigar el mecanismo detrás de las compuertas de electrolitos en las películas delgadas de dióxido de vanadio (VO2).
- Para determinar si la acumulación de portadores electrostáticos u otro mecanismo es responsable de la estabilización de fase.
Principales métodos:
- Crecimiento epitaxial de las películas delgadas VO2.
- Aplicación de cerraduras de electrolitos utilizando líquidos iónicos.
- Mediciones de transporte eléctrico en un amplio rango de temperaturas (hasta 5 K).
- Análisis de la composición y estructura del material después del gating.
Principales resultados:
- El cerramiento de electrolitos suprimió la transición de metal a aislante en VO2.
- La fase metálica del VO2 se estabilizó a temperaturas por debajo de 5 Kelvin, persistiendo incluso después de la eliminación del líquido iónico.
- El principal mecanismo identificado fue la creación de vacíos de oxígeno inducidos por el campo eléctrico, lo que llevó a la migración de oxígeno del VO2 al líquido iónico.
- Los portadores inducidos electrostáticamente no fueron el factor dominante.
Conclusiones:
- El estudio revela que la formación de vacíos de oxígeno, no el dopaje electrostático, es el principal impulsor de los efectos de entrada de líquido iónico en VO2.
- Este hallazgo requiere una reevaluación de las interpretaciones para experimentos similares que involucran el encierro de líquidos iónicos de materiales correlacionados.
- El mecanismo descubierto proporciona una comprensión crucial para el diseño de futuros dispositivos electrónicos basados en VO2 y óxidos similares.
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