Canted antiferromagnetism in phase-pure CuMnSb

Abstract

We report the low-temperature properties of phase-pure single crystals of the half-Heusler compound CuMnSb grown by means of optical float-zoning. The magnetization, specific heat, electrical resistivity, and Hall effect of our single crystals exhibit an antiferromagnetic transition at TN = 55 K and a second anomaly at a temperature T * ≈ 34 K. Powder and single-crystal neutron diffraction establish an ordered magnetic moment of (3.9 ± 0.1) µB/f.u., consistent with the effective moment inferred from the Curie-Weiss dependence of the susceptibility. Below TN, the Mn sublattice displays commensurate type-II antiferromagnetic order with propagation vectors and magnetic moments along 111 (magnetic space group R[I]3c). Surprisingly, below T * , the moments tilt away from 111 by a finite angle δ ≈ 11 • , forming a canted antiferromagnetic structure without uniform magnetization consistent with magnetic space group C[B]c. Our results establish that type-II antiferromagnetism is not the zero-temperature magnetic ground state of CuMnSb as may be expected of the face-centered cubic Mn sublattice.

High-pressure investigations on the semi-Heusler compound CuMnSb

“…For details on the crystal growth process and the metallurgical characterization, we refer to Ref. 7 High pressures were generated in a diamond anvil cell (DAC) made of CuBe alloy 34 by two opposing diamond anvils (1/6 carat, type Ia) with 0.5 mm diameter culets.…”

“…40 For pressures to 6.7 GPa, R(T) exhibits a weakly sublinear temperature dependence upon cooling followed by a pronounced drop or knee that indicates the onset of magnetic ordering, as found in previous resistivity, magnetic susceptibility, and specific heat studies on CuMnSb at ambient pressure. 7,10,41 The resistivity knee arises from the sudden decrease in the spin-disorder scattering when magnetic order sets in. In the present measurements the knee in R(T) is broadened by the pressure gradient across the sample arising from the non-hydrostatic pressure.…”

“…6 Recent transport, magnetization, and neutron scattering results on phase-pure single crystals of CuMnSb reveal a second anomaly at 34 K that results from a canting of the commensurate AFM structure without net magnetic moment. 7 Despite the structural similarities to half-metallic semi-Heusler compounds, density functional studies by Jeong et al 8 suggest that CuMnSb is a self-doped compensated semimetal and not a half-metal. The AFM phase in CuMnSb is particularly interesting due to its large ordered Mn moments, hallmarks of both local moment-itinerant mag-netism, and the stability of magnetic order to high magnetic fields.…”

Investigation of magnetic anisotropy and heat dissipation in thin films of compensated antiferromagnet CuMnAs by pump–probe experiment

“…The corresponding values for CuMnAs are not known, yet. Therefore, we used Debye temperature TD = 275 K and heat capacity at 300 K of 300 J kg -1 K-1 for a similar antiferromagnetic material CuMnSb [40]. The temperature dependencies of heat capacities (normalized to the values at 300 K) are shown in Fig.…”

Combined X-ray and neutron single-crystal diffraction in diamond anvil cells

“…It provides precise information on crystal and magnetic structures, including the reliable and accurate characterization of anisotropic displacement parameters in materials with highly absorbing elements. Typical investigations at HEiDi focus on (i) ionic conductors relevant for energy applications and data storage (Ceretti et al, 2018), (ii) superconductors (Jin et al, 2016), (iii) multiferroic materials (Regnat et al, 2018), (iv) small-molecule structures, in which hydrogen bridges play a key role as a structure building element (Truong et al, 2017(Truong et al, , 2018, or (v) complex zeolitic crystal structures (Gatta et al, 2018).…”