Band Structure and Transport Properties of CrO_2

Steven P. Lewis; Phillip B. Allen; Taizo Sasaki

doi:10.1103/physrevb.55.10253

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arXiv · mtrl-th/9608006

Band Structure and Transport Properties of CrO_2

Steven P. Lewis·Phillip B. Allen·Taizo Sasaki

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Abstract

Local Spin Density Approximation (LSDA) is used to calculate the energy bands of both the ferromagnetic and paramagnetic phases of metallic CrO_2. The Fermi level lies in a peak in the paramagnetic density of states, and the ferromagnetic phase is more stable. As first predicted by Schwarz, the magnetic moment is 2 μ_B per Cr atom, with the Fermi level for minority spins lying in an insulating gap between oxygen p and chromium d states ("half-metallic" behavior.) The A_1g Raman frequency is predicted to be 587 cm^{-1}. Drude plasma frequencies are of order 2eV, as seen experimentally by Chase. The measured resistivity is used to find the electron mean-free path l, which is only a few angstroms at 600K, but nevertheless, resistivity continues to rise as temperature increases. This puts CrO_2 into the category of "bad metals" in common with the high T_c superconductors, the high T metallic phase of VO_2, and the ferromagnet SrRuO_3. In common with both SrRuO_3 and Sr_2RuO_4, the measured specific heat γis higher than band theory by a renormalization factor close to 4.

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Steven P. Lewis, Phillip B. Allen, Taizo Sasaki. 1996-08-24. Band Structure and Transport Properties of CrO_2. https://doi.org/10.1103/physrevb.55.10253

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