Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Splitting of electronic spectrum in paramagnetic phase of itinerant ferromagnets and altermagnets

A. A. Katanin

Abstract

We study self-energy effects, induced by strong magnetic fluctuations in paramagnetic phase of strongly-correlated itinerant magnets within the density functional theory combined with the dynamical mean field theory (DFT+DMFT approach) and its non-local extension. As concrete examples, we consider $α$-iron, half metal CrO$_2$, van der Waals material CrTe$_2$, and altermagnet CrSb. We show that both local and non-local magnetic correlations yield splitting of the electronic spectrum in the paramagnetic phase, such that it closely resembles the DFT band structure in the ordered phase. The relative importance of non-local vs. local correlations depends on the proximity to half filling of $d$ states: closer to half filling, the role of local correlations increases. Although the obtained split bands do not possess a certain spin projection, their splitting suppresses spectral weight at the Fermi level. The obtained electronic states are also expected to be easily spin polarized by a weak external magnetic field.

Splitting of electronic spectrum in paramagnetic phase of itinerant ferromagnets and altermagnets

Abstract

We study self-energy effects, induced by strong magnetic fluctuations in paramagnetic phase of strongly-correlated itinerant magnets within the density functional theory combined with the dynamical mean field theory (DFT+DMFT approach) and its non-local extension. As concrete examples, we consider -iron, half metal CrO, van der Waals material CrTe, and altermagnet CrSb. We show that both local and non-local magnetic correlations yield splitting of the electronic spectrum in the paramagnetic phase, such that it closely resembles the DFT band structure in the ordered phase. The relative importance of non-local vs. local correlations depends on the proximity to half filling of states: closer to half filling, the role of local correlations increases. Although the obtained split bands do not possess a certain spin projection, their splitting suppresses spectral weight at the Fermi level. The obtained electronic states are also expected to be easily spin polarized by a weak external magnetic field.

Paper Structure

This paper contains 2 sections, 25 equations, 5 figures.

Table of Contents

  1. Derivation of Eq. (\ref{['SEnonloc']})
  2. Spectral density of iron at $\beta=4$ eV$^{-1}$

Figures (5)

  • Figure 1: (Color online) Band structure of iron in the ferromagnetic (brown and blue solid lines for different spin projections) and non-magnetic (red dashed lines) phases, compared to the spectral density in DMFT approach (a) and the approach, accounting for the non-local corrections to the self-energy (b) at $\beta=4.6$ eV$^{-1}$. Yellow arrows in (b) show position of bands, formed by spin fluctuations in paramagnetic phase. Inset in (a) shows the path in the Brillouin zone.
  • Figure 2: (Color online) Band structure of CrO$_2$ in the ferromagnetic phase (brown and blue solid lines for different spin projections) and low-energy (mostly $d$) states in non-magnetic phase (circles), compared to the spectral density in DFT+DMFT approach (top) and the approach, accounting the non-local corrections to the self-energy (bottom) at $\beta=6$ eV$^{-1}$.
  • Figure 3: (Color online) Band structure of CrTe$_2$ in the ferromagnetic (violet and blue solid lines for different spin projections) and non-magnetic (black dashed lines) phases, compared to the spectral density in DMFT approach
  • Figure 4: (Color online) Band structure of altermagnet CrSb in the magnetic (dark solid and dashed lines for different spin projections) and non-magnetic (red dashed lines) phases, compared to the spectral density in DMFT approach (top) and the approach, accounting the non-local corrections to the self-energy (bottom) at $\beta=5$ eV$^{-1}$.
  • Figure S1: (Color online) Band structure of iron in the ferromagnetic (solid lines) and non-magnetic (dashed lines) phases, compared to the spectral density in DMFT approach (left) and the approach, accounting the non-local corrections to the self-energy (right) at $\beta=4$ eV$^{-1}$. Yellow arrows show position of bands, formed by spin fluctuations in paramagnetic phase.