Phase stability in SmB$_6$

TL;DR

This study examines how Sm-deficiency in flux-grown SmB$_6$ affects its local structure and electronic properties, revealing that the overall structure remains stable despite significant Sm vacancies, with local effects on surface conductance.

Contribution

It provides detailed analysis showing the persistence of SmB$_6$'s local structure despite Sm-deficiency, highlighting local versus global effects on electronic properties.

Findings

Local structure remains stable with Sm deficiency.

Surface conductance is affected locally by Sm vacancies.

Global electronic properties are resilient to Sm deficiency.

Abstract

We investigate flux-grown Sm-deficient Sm$_x$B$_6$ ($x < 1$) by global and local tools, including X-ray diffraction (XRD), electronic transport, and scanning tunneling microscopy (STM) and spectroscopy (STS). All these tools indicate a remarkable persistence of the SmB$_6$ local structure in the flux-grown samples even for nominal Sm concentrations as low as $x=0.75$. As a consequence, the overall electronic properties of Sm$_x$B$_6$, and particularly the surface conductance at low temperature, is only affected locally by the Sm-deficiency.