Magnetic Field-Induced Superconductor-Insulator-Metal Transition in an Organic Conductor: An Infrared Magneto-Optical Imaging Spectroscopy

TL;DR

This study observes a magnetic field-induced superconductor-insulator-metal transition in an organic conductor using infrared magneto-optical imaging, revealing phase coexistence and the effects of sample inhomogeneity.

Contribution

It demonstrates the magnetic field-induced SIMT in a Mott boundary organic conductor and links it to sample inhomogeneity and ethylene end group disorder.

Findings

Coexistence of metallic and insulating phases observed.

SIMT occurs on part of the sample surface under magnetic field.

Transition influenced by sample inhomogeneity and disorder.

Abstract

The magnetic field-induced superconductor-insulator-metal transition (SIMT) in partially deuterated $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Br, which is just on the Mott boundary, has been observed using the infrared magneto-optical imaging spectroscopy. The infrared reflectivity image on the sample surface revealed that the metallic (or superconducting) and insulating phases coexist and they have different magnetic field dependences. One of the magnetic field dependence is SIMT that appeared on part of the sample surface. The SIMT was concluded to originate from the balance of the inhomogenity in the sample itself and the disorder of the ethylene end groups resulting from fast cooling.