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Shubnikov–de Haas oscillations in half-metallic ferromagnetic CrO2 epitaxial films

Vineetha S. Bheemarasetty1,*, David T. Plouff2, Xinhao Wang2, Benjamin J. Brown1, H. Minh Cao1, John Q. Xiao2, and Gang Xiao1,†

  • *Contact author: vineetha_bheemarasetty@brown.edu
  • †Contact author: gang_xiao@brown.edu
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Phys. Rev. B 111, 214440 – Published 27 June, 2025

DOI: https://doi.org/10.1103/v73x-5ptd

Abstract

We present a study of the low-temperature, high-field magnetotransport behavior of epitaxially grown CrO2 thin films on (100) TiO2 substrates. Electron transport measurements confirm high sample quality, with a residual resistivity ratio as large as 45. A logarithmic fit of the low-temperature regime yields a T4.5 power law, indicative of the elusive double-magnon scattering in half-metallic ferromagnets. Angle-dependent anisotropic magnetoresistance (AMR) measurements reveal a large projected density of states along [001] with a maximum AMR value of 2.4%. Pronounced, axis-dependent Shubnikov–de Haas (SdH) oscillations are observed in the longitudinal magnetoresistance (MR), with discrete Landau levels mapped at various tilt angles of the magnetic field. Their angular dependence follows a 1/cosθ relation pointing to a highly anisotropic Fermi surface, and amplitude scaling adheres closely to the thermodynamic Lifshitz-Kosevich formalism. The out-of-plane MR reaches 6.58%, the largest reported for CrO2 thin films. Notably, this study presents an observation of SdH oscillations in a half-metallic oxide with near-perfect spin polarization, a significant advancement in the field of spintronics.

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Phys. Rev. B 111, 214440– Published 27 June, 2025
  • Received 18 February 2025
  • Accepted 28 May 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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