Anisotropic Transport and Magnetic Properties of Charge-Density-Wave Materials RSeTe sub(2) (R=La, Ce, Pr, Nd)

Single crystals of RSeTe sub(2) (R = La, Ce, Pr, Nd) are synthesized using LiCl/RbCl flux. Transport and magnetic properties in the directions parallel and perpendicular to the a-c plane are investigated. We find that the resistivity anisotropy [rho] sub([perpendicular])/[rho] sub(||) lies in the range 486-615 for different compounds at 2K, indicating the highly two-dimensional character. In both the orientations, the charge-density-wave transitions start near T sub(CDW) = 284(3)K, 316(3) K, 359(3) K for NdSeTe sub(2), PrSeTe sub(2), CeSeTe sub(2), respectively, with a considerable increase in dc resistivity. While for LaSeTe sub(2), no obvious resistivity anomaly is observed up to 380 K. The value of T sub(CDW) increases monotonically with the increasing lattice parameters. Below T sub(CDW), slight anomalies can be observed in NdSeTe sub(2), PrSeTe sub(2) and CeSeTe sub(2) with onset temperature at 193(3)K, 161(3) K, 108(3)K, respectively, decreasing as lattice parameters increase. Magnetic susceptibility measurements show that the valence state of rare earth ions are trivalence in these compounds. Antiferromagnetic-type magnetic order is formed in CeSeTe sub(2) at 2.1 K, while no magnetic transition is observed in PrSeTe sub(2) and NdSeTe sub(2) down to 1.8K.