Half-Metallic Ferromagnetism and the spin polarization in CrO$_2$

TL;DR

This paper combines advanced electronic structure calculations to study CrO$_2$, revealing non-quasiparticle states at finite temperatures and confirming its half-metallic nature and high spin polarization.

Contribution

It introduces a combined approach using Dynamical Mean Field Theory and Variational Cluster Approach to analyze spin polarization and electronic states in CrO$_2$.

Findings

Existence of non-quasiparticle states near the Fermi energy at finite temperature.

Confirmation of half-metallic nature of CrO$_2$ at zero temperature.

Qualitative description of spin polarization in CrO$_2$.

Abstract

We present electronic structure calculations in combination with local and non-local many-body correlation effects for the half-metallic ferromagnet CrO$_2$. Finite-temperature Dynamical Mean Field Theory results show the existence of non-quasiparticle states, which were recently observed as almost currentless minority spin states near the Fermi energy in resonant scattering experients. At zero temperatures, Variational Cluster Approach calculations support the half-metallic nature of CrO$_2$ as seen in superconducting point contact spectroscopy. The combination of these two techniques allowed us to qualitatively describe the spin-polarization in CrO$_2$.