Band filling dependence of the Curie temperature in CrO2

I. V. Solovyev; I. V. Kashin; V. V. Mazurenko

doi:10.1088/0953-8984/28/21/216001

paper

Band filling dependence of the Curie temperature in CrO2

arXiv:1601.05171 · doi:10.1088/0953-8984/28/21/216001

Abstract

Rutile CrO $_{2}$ is an important half-metallic ferromagnetic material, which is also widely used in magnetic recording. In an attempt to find the conditions, which lead to the increase the Curie temperature ( $T_{C}$ ), we study theoretically the band-filling dependence of interatomic exchange interactions in the rutile compounds. For these purposes, we use the effective low-energy model for the magnetic $t_{2 g}$ bands, derived from the first-principles electronic structure calculations in the Wannier basis, which is solved by means of dynamical mean-field theory. After the solution, we calculate the interatomic exchange interactions, by using the theory of infinitesimal spin rotations, and evaluate $T_{C}$ . We argue that, as far as the Curie temperature is concerned, the band filling realized in CrO $_{2}$ is far from being the optimal one and much higher $T_{C}$ can be obtained by decreasing the number of $t_{2 g}$ electrons ( $n$ ) via the hole doping. We find that the optimal $n$ is close to $1$ , which should correspond to the case of VO $_{2}$ , provided that it is crystallized in the rutile structure. This finding was confirmed by using the experimental rutile structure for both CrO $_{2}$ and VO $_{2}$ and reflects the general tendency towards ferromagnetism for the narrow-band compounds at the beginning of the band filling. In particular, our results suggest that the strong ferromagnetism can be achieved in the thin films of VO $_{2}$ , whose crystal structure is controlled by the substrate.

13 pages, 6 figures

Band filling dependence of the Curie temperature in CrO2

Abstract

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