Low-temperature properties of single-crystal CrB$_{2}$

Bauer, A.; Regnat, A.; Pfleiderer, C.; Pedersen, B.; Kuneš, J.; Blum, C. G. F.; Meven, M.; Gottlieb-Schönmeyer, S.; Wurmehl, S.

doi:10.1103/PhysRevB.90.064414

Journal Article

FZJ-2015-00762

Low-temperature properties of single-crystal CrB$_{2}$

Bauer, A. (Corresponding Author) ; Regnat, A. ; Blum, C. G. F. ; Gottlieb-Schönmeyer, S. ; Pedersen, B. ; Meven, M.FZJ* ; Wurmehl, S. ; Kuneš, J. ; Pfleiderer, C.

2014
APS College Park, Md.

Physical review / B 90(6), 064414 (2014) [10.1103/PhysRevB.90.064414]

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Please use a persistent id in citations: http://hdl.handle.net/2128/9108 doi:10.1103/PhysRevB.90.064414

Abstract: 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, ρxx, Hall effect, ρxy, and specific heat, C, are characteristic of an exchange-enhanced Fermi liquid ground state, which develops a slightly anisotropic spin gap Δ≈220~K below TN=88~K. This observation is corroborated by the absence of a Curie dependence in the magnetisation for T→ 0 reported in the literature. Comparison of C with dxx=dT , where we infer lattice contributions from measurements of VB2, reveals strong antiferromagnetic spin fluctuations with a characteristic spin fluctuation temperature Tsf≈257~K in the paramagnetic state, followed by a pronounced second order mean-field transition at TN, and unusual excitations around ≈TN/2. The pronounced anisotropy of ρxx above TN is characteristic of an easy-plane anisotropy of the spin fluctuations consistent with the magnetisation. The ratio of the Curie-Weiss to the Neel temperatures, f=−ΘCW/TN≈ 8.5, inferred from the magnetisation, 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.

Keyword(s): Basic research (1st) ; Key Technologies (1st) ; Others (1st) ; Information Technology and Functional Materials (1st) ; Crystallography (2nd) ; Magnetism (2nd) ; Condensed Matter Physics (2nd)