Magnetic and electrical transport properties of the single-crystalline half-Heusler antiferromagnet DyNiSb

Abstract

High-quality single crystals of the half-Heusler compound DyNiSb were investigated for their low temperature thermodynamic and magnetotransport properties. Magnetic susceptibility, heat capacity, and electrical resistivity measurements revealed two distinct magnetic phase transitions at TN1 = 7.3 K and TN2 = 3.4 K, contrasting with previous reports on polycrystalline samples, which identified only a single transition near TN2 . Moreover, the studied samples were found to exhibit Metal like conductivity, at odds with a semiconducting behavior reported for the polycrystals. Magnetoresistance measurements performed in both transverse and longitudinal configurations revealed in small magnetic fields a weak antilocalization effect that diminishes with increasing temperature, giving way to a positive, monotonic magnetoresistance at high temperatures. Angular-dependent resistivity studies showed a crossover from fourfold to twofold symmetry with increasing magnetic-field strength, suggesting a field-induced reconstruction of the Fermi surface. Our findings highlight a complex magnetic and electrical transport behavior in DyNiSb, highly sensitive to structural disorder and easily tunable by external magnetic field.

Figures (9)

• Figure 1: (a) Crystallographic unit cell of DyNiSb. (b) Photograph of as-grown single crystals of DyNiSb. (c) Laue diffraction pattern of DyNiSb single crystal, collected for the (001) plane.
• Figure 2: (a) Temperature dependence of the reciprocal molar magnetic susceptibility of single-crystalline DyNiSb measured in a magnetic field of 0.5 T applied along the [001] direction. The solid red line represents the Curie-Weiss fit described in the text. (b) Low-temperature variations of the magnetic susceptibility of DyNiSb measured along the [001] direction in different magnetic fields upon cooling the sample in zero (ZFC) and applied (FC) field. Black arrows mark the transition temperatures. For a sake of clarity, the data obtained in $B=$ 1 T and 3 T were shifted upwards by offset values of 0.07 and 0.14 emu mol$^{-1}$Oe$^{-1}$, respectively. (c) Temperature dependence of the real part of the dynamical susceptibility measured in zero steady magnetic field in an ac field of 0.5 mT alternating with different frequencies. The inset presents the the temperature variation of the imaginary part of the ac magnetic susceptibility taken in the same conditions. (d) Magnetization isotherms measured for single-crystalline DyNiSb at various temperatures in magnetic fields applied along the [001] axis. The inset shows the data taken at $T=$ 2 K with increasing and decreasing the magnetic field strength.
• Figure 3: (a) Temperature variations of the specific heat of DyNiSb and LuNiSb. The black solid line represents the Debye-Einstein fit described in the text. The inset shows the specific heat over temperature data of DyNiSb in the region of AFM transitions. (b) Temperature dependence of the sum of magnetic and electronic contributions to the specific heat of DyNiSb estimated as described in the text. The inset presents the temperature variation of the magnetic entropy.
• Figure 4: (a) Temperature dependence of the electrical resistivity of single-crystalline DyNiSb measured along the crystallographic direction [010] presented on a semi-logarithmic scale. The red symbols represent the temperature derivative of the resistivity (unit-less representation). The inset shows the low-temperature data. (b) The magnetoresistance isotherms taken for DyNiSb at various temperatures with the current $\textbf{I}$$\parallel$ [010] and magnetic field aligned along the [001] axis. (c) The magnetoresistance isotherms of DyNiSb measured in parallel configuration of the electric current and magnetic field $\textbf{I}$$\parallel$$\textbf{B}$$\parallel$ [010]. (d) The magnetoconductivity isotherms of DyNiSb calculated from the longitudinal magnetoresistance data collected as in panel (c) at low temperatures and in weak magnetic fields. The solid lines represent the Hikami-Larkin-Nagaoka fit described in the text. The inset displays the temperature variations of the fitting parameters.
• Figure 5: Magnetic field variations of the electrical resistivity of single-crystalline DyNiSb measured at different temperatures with electric current $\textbf{I}$$\parallel$ [010] and magnetic field aligned along the [001] axis. Solid lines represent the dGF fits discussed in the text. The inset shows the temperature dependence of the parameter $\rho_0^\infty$ derived from the dGF model.