Determining the Anisotropic Exchange Coupling of CrO_2 via First-Principles Density Functional Theory Calculations

Abstract

We report a study of the anisotropic exchange interactions in bulk CrO_2 calculated from first principles within density functional theory. We determine the exchange coupling energies, using both the experimental lattice parameters and those obtained within DFT, within a modified Heisenberg model Hamiltonian in two ways. We employ a supercell method in which certain spins within a cell are rotated and the energy dependence is calculated and a spin-spiral method that modifies the periodic boundary conditions of the problem to allow for an overall rotation of the spins between unit cells. Using the results from each of these methods, we calculate the spin-wave stiffness constant D from the exchange energies using the magnon dispersion relation. We employ a Monte Carlo method to determine the DFT-predicted Curie temperature from these calculated energies and compare with accepted values. Finally, we offer an evaluation of the accuracy of the DFT-based methods and suggest implications of the competing ferro- and antiferromagnetic interactions.

10 pages, 13 figures

References in corpus (2)

• Half-Metallic Ferromagnetism and the spin polarization in CrO${}_2$
• Determination of exchange constants of Heusler compounds by Brillouin light scattering spectroscopy: application to Co${}_2$MnSi

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• Electronic Structure of Magnetic Semiconductor CdCr_2Te_4: A Possible Spin-Dependent Symmetry Filter
• Linear response theories for interatomic exchange interactions
• Magnetic properties of half metal from the paramagnetic phase: DFT+DMFT study of exchange interactions in CrO${}_2$