Evidence for High-Temperature Superconductivity in Doped Laser-Processed Sr-Ru-O

TL;DR

This study reports the discovery of signatures of superconductivity above 200K in a specially processed Sr2RuO4-based material, involving laser micromachining and doping, with evidence from resistance and magnetic measurements.

Contribution

The paper introduces a novel processing method for Sr2RuO4 that results in high-temperature superconductivity signatures above 200K, which is significantly higher than the known Tc of the unprocessed material.

Findings

Superconductivity signatures observed above 200K in processed Sr2RuO4.

Critical temperature decreases with increased measuring current.

Maximum Tc observed up to 250K from magneto-optical and SQUID measurements.

Abstract

We have discovered that samples of a new material produced by special processing of crystals of Sr2RuO4 (which is known to be a triplet superconductor with Tc values ~1.0-1.5K) exhibit signatures of superconductivity (zero DC resistance and expulsion of magnetic flux) at temperatures exceeding 200K. The special processing includes deposition of a silver coating and laser micromachining; Ag doping and enhanced oxygen are observed in the resultant surface layer. The transition, whether measured resistively or by magnetic field expulsion, is broad. When the transition is registered by resistive methods, the critical temperature is markedly reduced when the measuring current is increased. The resistance disappears by about 190K. The highest value of Tc registered by magneto-optical visualization is about 220K and even higher values (up to 250K) are indicated from the SQUID-magnetometer measurements.