Phase Diagram for Light-Induced Superconductivity in κ-(ET)_{2}-X.

M Buzzi,M.-S Nam,K Miyagawa,G Jotzu,A Cavalleri,A Ardavan,D Nicoletti,J A Schlueter,A Henderson,K Kanoda,S Fava,T Siegrist

doi:10.1103/physrevlett.127.197002

Abstract

Resonant optical excitation of certain molecular vibrations in κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Br has been shown to induce transient superconductinglike optical properties at temperatures far above equilibrium T_{c}. Here, we report experiments across the bandwidth-tuned phase diagram of this class of materials, and study the Mott insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl and the metallic compound κ-(BEDT-TTF)_{2}Cu(NCS)_{2}. We find nonequilibrium photoinduced superconductivity only in κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Br, indicating that the proximity to the Mott insulating phase and possibly the presence of preexisting superconducting fluctuations are prerequisites for this effect.

Highlights

Synthetic metals of the κ-ðBEDT-TTFÞ2X family exhibit high-temperature unconventional superconductivity [1,2,3] and bear some parallels with the physics of high-Tc cuprates
We find nonequilibrium photoinduced superconductivity only in κ-ðBEDT-TTFÞ2Cu1⁄2NðCNÞ2Br, indicating that the proximity to the Mott insulating phase and possibly the presence of preexisting superconducting fluctuations are prerequisites for this effect
Because of the layered structure, the normal state optical properties resemble those of an insulator across the ET layers [7], whereas parallel to the planes the optical conductivity is insulating for the Mott phase of κ-Cl and metallic for κ-Br and κ-NCS

Summary

Introduction

Synthetic metals of the κ-ðBEDT-TTFÞ2X family exhibit high-temperature unconventional superconductivity [1,2,3] and bear some parallels with the physics of high-Tc cuprates. Resonant optical excitation of certain molecular vibrations in κ-ðBEDT-TTFÞ2Cu1⁄2NðCNÞ2Br has been shown to induce transient superconductinglike optical properties at temperatures far above equilibrium Tc. Here, we report experiments across the bandwidth-tuned phase diagram of this class of materials, and study the Mott insulator κ-ðBEDT-TTFÞ2Cu1⁄2NðCNÞ2Cl and the metallic compound κ-ðBEDT-TTFÞ2CuðNCSÞ2.

Results

Conclusion