Magnetism in Iron at High Temperatures

Abstract

Magnetism in iron at high temperature is investigated by calculating the total electronic band-structure energy for four types of spin arrangements. A slow smooth spatial variation of spin direction costs relatively little energy and the atomic moment $m$ is reduced only \ensuremath{\sim} 10%. More rapid variations have considerably higher energy, which may explain the high degree of short-range order and small $\ensuremath{\delta}m$ observed at $T\ensuremath{\gtrsim}{T}_{\mathrm{C}}$. Other aspects are also discussed.