1s2p Resonant Inelastic X-ray Scattering Magnetic Circular Dichroism as a probe for the local and non-local orbitals in CrO 2

Abstract

We have determined the magnetic ground state of the half-metal CrO2 based on 1s2p Resonant Inelastic X-ray Scattering Magnetic Circular Dichroism (RIXS-MCD) experiments. The two-dimensional RIXS-MCD map displays the 1s X-ray absorption spectrum combined with the 1s2p X-ray emission decay, where there is a large MCD contrast in the final state involving the 2p core hole. Our measurements show that the Cr K pre-edge structure is dominated by dipolar contributions and the quadrupole peak is invisible in direct K pre-edge absorption. Using RIXS-MCD, we reveal that the quadrupole 1s3d pre-edge has a large MCD contrast, which appears at lower energy with respect to the K pre-edge maximum. We use crystal field multiplet calculations to model the excitonic RIXS-MCD spectral shape in tetragonal (D4h) symmetry. The RIXS-MCD is strongly sensitive to the ground state distortion of the Cr4+ sites. The calculations of the RIXS-MCD maps suggest that the 3d spin–orbit interaction is fully quenched (ζ3d = 0 meV) and the ground state electron configuration must contain a 3B2g (D4h) contribution, which is required to explain the appearance of the Magnetic Circular Dichroism (MCD) in the Cr K pre-edge. This is in apparent contrast with the compressed tetragonal distortion.