Anisotropy in magnetic and transport properties of LaTSb₃ (T=Cr, V)

We report measurements of anisotropy in magnetic susceptibility, magnetization, and electrical resistivity using single crystals of LaTSb₃ (T=Cr,V). LaTSb₃ is a quasi-two-dimensional system with an orthorhombic crystal structure (space group Pbcm), possessing a rich phase diagram with a ferromagnetic transition at T_C=132 K due to the ordering of the Cr ions. In order to investigate LaTSb₃, magnetic susceptibility and magnetization for fields up to 55 kG and in the temperature range of 2–350 K have been measured with the field aligned to the three principle axes. The electrical resistivity of LaCrSb₃ has been measured for currents parallel to the a, b, and c axes in the temperature range 5–295 K, as well as magnetoresistances at 20 k and 60 kG along the b axis. Isostructural LaVSb₃ is found have no transitions in either the magnetization or the resistivity; therefore, it is presented as a nonmagnetic counterpart. Just below T_C, the easy axis is found to be within the b-c plane in the direction of the magnetic field. As the system is further cooled, there is a crossover from quasi-two-dimensional (2D) to 3D anisotropy below a characteristic temperature T^*, and the easy axis of magnetization becomes oriented along the b axis. Furthermore, it is found that T^* decreases linearly as the magnetic field is increased, and is suppressed with a field H>3.7 kG. A high-temperature antiferromagnetic transition is found at T_N=98 K. The value of T_N is found to be independent of the applied magnetic field up to H=0.25 kG, at which point this antiferromagnetic phase is suppressed.