Temperature dependence of magnetism near defects in SrB_6

TL;DR

This study investigates how magnetic moments in SrB_6 change with temperature near defects using spin-polarized calculations, revealing rapid decay and suggesting other impurities may cause high-temperature magnetism.

Contribution

It provides a detailed computational analysis of temperature effects on defect-induced magnetism in SrB_6, challenging previous high Curie temperature reports.

Findings

Magnetic moments decay quickly with temperature near defects.

Electronic Fermi-Dirac effects alone cannot explain high Curie temperatures.

Impurities other than vacancies or La may be responsible for observed magnetism.

Abstract

The T-dependence of magnetic moments in SrB_6 is studied through spin-polarized band calculations for a supercell of Sr_{27}B_{156} containing a B_6 vacancy. The magnetic moment decays rather quickly with T despite the fact that only electronic Fermi-Dirac effects are included. This result and the T-dependence of moments near a La impurity can hardly explain the reports of a very high Curie temperature in hexaborides, but suggest that the magnetism is caused by some other type of impurity.