Crystal orientation and thickness dependence of superconductivity on tetragonal FeSe1-x thin films

TL;DR

This study investigates how crystal orientation and thickness influence superconductivity in tetragonal FeSe1-x thin films, revealing temperature-dependent growth behaviors and the importance of structural deformation for superconductivity.

Contribution

It demonstrates the fabrication of superconducting FeSe1-x thin films with controlled orientation and thickness, highlighting the role of growth temperature and structural deformation.

Findings

Superconductivity depends on film thickness at 320°C.

At 500°C, films grow along (101) with minimal thickness effect.

Growth temperature influences crystal orientation and superconducting properties.

Abstract

Superconductivity was recently found in the simple tetragonal FeSe structure. Recent studies suggest that FeSe is unconventional, with the symmetry of the superconducting pairing state still under debate. To tackle these problems, clean single crystals and thin films are required. Here we report the fabrication of superconducting beta-phase FeSe1-x thin films on different substrates using a pulsed laser deposition (PLD) technique. Quite interestingly, the crystal orientation, and thus, superconductivity in these thin films is sensitive to the growth temperature. At 320C, films grow preferably along c-axis, but the onset of superconductivity depends on film thickness. At 500C, films grow along (101), with little thickness dependence. These results suggest that the low temperature structural deformation previously found is crucial to the superconductivity of this material.