Numerical Study of Multiple Helical Spin Density Waves and Vortex Spin Structures in Itinerant Electron System

TL;DR

This paper investigates complex magnetic structures like multiple helical spin density waves and vortex formations in itinerant electron systems using the Hubbard model, revealing various stable phases near the Stoner instability line.

Contribution

It introduces a comprehensive analysis of multiple SDW and vortex structures in itinerant electrons, identifying new stable phases and their electronic stability mechanisms.

Findings

Identification of 2Q, 3Q, 4Q, and 12Q SDW structures.

Discovery of a new 12Q SDW with vortex and partial order features.

Phase diagram showing stability regions near the Stoner line.

Abstract

Multiple spin density waves and related vortex-type magnetic structures in the itinerant electron system with inversion symmetry have been investigated on the basis of the Hubbard model and the generalized Hartree-Fock approximation combined with the recursion method. Possible magnetic phase diagram on the fcc lattice is presented in the space of the Coulomb interaction strength and the electron occupation number. It is found that the 2Q multiple helical spin density waves (SDW) with half-skyrmion half-antiskyrmion paired structure, the 3Q multiple helical SDW with 3 dimensional type vortex structure, the 4Q multiple SDW with partially ordered state, and a new type of 12Q multiple SDW showing both the half-skyrmion-type vortex structure and the partially ordered state can be stabilized around the Stoner instability line. The stability of their structures is explained on the basis of their electronic structures.