Band filling dependence of the Curie temperature in CrO2

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 (\(T_{\rm C}\)), we study theoretically the band-filling dependence of interatomic exchange i...

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Bibliographic Details
Published in:arXiv.org 2016-01
Main Authors: Solovyev, I V, Kashin, I V, Mazurenko, V V
Format: Article
Language:English
Subjects:
Banded structure
Crystal structure
Crystallization
Curie temperature
Electronic structure
Exchanging
Ferromagnetic materials
First principles
Magnetic recording
Magnetism
Mean field theory
Rutile
Substrates
Temperature dependence
Thin films
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Summary: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 (\(T_{\rm C}\)), 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 \(t_{2g}\) 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 \(T_{\rm C}\). 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 \(T_{\rm C}\) can be obtained by decreasing the number of \(t_{2g}\) 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.
ISSN:2331-8422
DOI:10.48550/arxiv.1601.05171