Anomalous phonon lifetime shortening in paramagnetic CrN caused by magneto-lattice coupling: A combined spin and ab initio molecular dynamics study

TL;DR

This study investigates how spin fluctuations and lattice vibrations interact in paramagnetic CrN, revealing that their dynamic coupling shortens phonon lifetimes and explains anomalous thermal conductivity behavior.

Contribution

It introduces a combined spin and ab initio molecular dynamics approach to reveal non-adiabatic effects in phonon lifetimes caused by magneto-lattice coupling.

Findings

Phonon lifetimes are significantly shortened due to dynamic spin-lattice coupling.

The approach explains the temperature dependence of thermal conductivity in magnetic semiconductors.

Non-adiabatic effects are crucial in understanding phonon behavior in paramagnetic materials.

Abstract

We study the mutual coupling of spin fluctuations and lattice vibrations in paramagnetic CrN by combining atomistic spin dynamics and ab initio molecular dynamics. The two degrees of freedom are dynamically coupled leading to non-adiabatic effects. Those effects suppress the phonon life times at low temperature compared to an adiabatic approach. The here identified dynamic coupling provides an explanation for the experimentally observed unexpected temperature dependence of the thermal conductivity of magnetic semiconductors above the magnetic ordering temperature.