Phenomenological Theory of Multiple Spin Density Waves in fcc Transition Metals

TL;DR

This paper develops a phenomenological Ginzburg-Landau model to analyze the stability of multiple spin density wave states in fcc transition metals, predicting various 3Q states and comparing them with experimental data.

Contribution

It introduces a phenomenological free energy framework to predict and compare the stability of multiple spin density wave states in fcc metals, including novel 3Q configurations.

Findings

3Q MSDW states are always stabilized over 2Q and 1Q states.

Magnetic moments are largest in 3Q states.

Results align with previous ground-state calculations and suggest explanations for fcc-Fe data.

Abstract

The relative stability among the multiple spin density wave (MSDW) states in fcc transition metals has been investigated on the basis of a Ginzburg-Landau type of free energy with terms up to the fourth order in magnetic moments. Obtained magnetic phase diagrams in the space of expansion coefficients indicate the possibility of various 3Q MSDW states in fcc transition metals: the commensurate 3Q state, the incommensurate linear 3Q state, and the incommensurate helical 3Q state. It is shown that these 3Q states are always stabilized, when they are compared with the corresponding 2Q and 1Q states, and their magnetic moment amplitudes are the largest among those of the three states. The results are compared with previous results of the ground-state calculations, and possible scenarios to explain the experimental data of fcc-Fe are proposed.