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Magnetostructural effects and phase transition in Cr_2O_3 under pressure

Alexander Yu. Dobin·Wenhui Duan·Renata M. Wentzcovitch
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Abstract

We have successfully calculated the electronic and structural properties of chromia (Cr_2O_3) in the Local Spin Density Approximation (LSDA). We predict a transformation from the corundum to the Rh_2O_3(II) structure around 15 GPa in the anti-ferromagnetic (AFM) phase as well as in the paramagnetic (PM) insulating state which occurs above the Neel temperature (T_N). This transition is relevant to interpreting the optical anomalies observed in the absorption spectrum of ruby under pressure. We have modeled the structural properties of the PM state using a Landau-like expansion of the magnetostriction energy. This treatment correctly describes the structural anomalies across T_N in the corundum phase and indicates that the AFM and PM insulating states should have distinct compressive behaviors.

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Alexander Yu. Dobin, Wenhui Duan, Renata M. Wentzcovitch. 2000-06-14. Magnetostructural effects and phase transition in Cr_2O_3 under pressure. https://doi.org/10.1103/physrevb.62.11997

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