Two-Dimensional Intrinsic Half-Metals With Large Spin Gaps.
basic_science · Level V
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- Record sourced from PubMed, PMID 28745061.
- Also identified by DOI 10.1021/acs.nanolett.7b01367.
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Abstract
Through a systematic search of all layered bulk compounds combined with density functional calculations employing hybrid exchange-correlation functionals, we predict a family of three magnetic two-dimensional (2D) materials with half-metallic band structures. The 2D materials, FeCl<sub>2</sub>, FeBr<sub>2</sub>, and FeI<sub>2</sub>, are all sufficiently stable to be exfoliated from bulk layered compounds. The Fe<sup>2+</sup> ions in these materials are in a high-spin octahedral d<sup>6</sup> configuration leading to a large magnetic moment of 4 μ<sub>B</sub>. Calculations of the magnetic anisotropy show an easy-plane for the magnetic moment. A classical XY model with nearest neighbor coupling estimates critical temperatures, T<sub>c</sub>, for the Berezinskii-Kosterlitz-Thouless transition ranging from 122 K for FeI<sub>2</sub> to 210 K for FeBr<sub>2</sub>. The quantum confinement of these 2D materials results in unusually large spin gaps, ranging from 4.0 eV for FeI<sub>2</sub> to 6.4 eV for FeCl<sub>2</sub>, which should defend against spin current leakage even at small device length scales. Their purely spin-polarized currents and dispersive interlayer interactions should make these materials useful for 2D spin valves and other spintronic applications.