2014/08/13 by A. Bauer, Andreas Bauer, Alexander Regnat +13 · 1 citation
Materials Science · Physics and Astronomy · #Boron and Carbon Nanomaterials Research #Computer science #Iron-based superconductors research #Rare-earth and actinide compounds #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.90.064414
published as Phys. Rev. B 90, 064414 (2014) · 15 pages, 9 figures
openalex publication_date 2014/08/13 · arxiv created 2014/12/04 · arxiv updated 2014/12/05 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the low-temperature properties of 11B-enriched single-crystal CrB2 as prepared from high-purity Cr and B powder by a solid-state reaction and optical float zoning. The electrical resistivity, \ensuremathρxx, Hall effect, \ensuremathρxy, and specific heat, C, are characteristic of an exchange-enhanced Fermi liquid ground state, which develops a slightly anisotropic spin gap \ensuremathΔ\ensuremath≈220\phantom\rule0.28em0exK below TN=88\phantom\rule0.28em0exK. This observation is corroborated by the absence of a Curie dependence in the magnetization for T\ensuremath→0 reported in the literature. Comparison of C with d\ensuremathρxx/dT, where we infer lattice contributions from measurements of VB2, reveals strong antiferromagnetic spin fluctuations with a characteristic spin fluctuation temperature Tsf\ensuremath≈257\phantom\rule0.28em0exK in the paramagnetic state, followed by a pronounced second-order mean-field transition at TN, and unusual excitations around \ensuremath≈TN/2. The pronounced anisotropy of \ensuremathρxx above TN is characteristic of an easy-plane anisotropy of the spin fluctuations consistent with the magnetization. The ratio of the Curie-Weiss to the N\stackrel\ifmmode \acute\else '\fieel temperatures, f=\ensuremath-\ensuremathΘCW/TN\ensuremath≈8.5, inferred from the magnetization, implies strong geometric frustration. All physical properties are remarkably invariant under applied magnetic fields up to 14 T, the highest field studied. In contrast to earlier suggestions of local-moment magnetism our study identifies CrB2 as a weak itinerant antiferromagnet par excellence with strong geometric frustration.