Anisotropic magnetic properties and anomalous transport properties of RCuAs2 single crystals (R = Y, La-Nd, Sm, Gd-Yb)

Single crystals of RCuAs2 (R = Y, La-Nd, Sm, Gd-Yb) were synthesized, and powder XRD measurements, as well as measurements of magnetization, specific heat, resistivity, and Hall resistivity, were performed. LaCuAs2 crystallizes into a body-centred tetragonal structure, while all other compounds crystallize into a primitive tetragonal structure. The unit cell volume across the series follows the well-known Lanthanide contraction. Magnetization measurements clearly show large anisotropy across the series, mostly due to the CEF effect. Magnetic susceptibility measurements confirm that the rare-earth ions are in the 3+ valence state, while low temperature data indicates magnetic ordering, confirmed by specific heat measurements. Magnetization isotherms indicate metamagnetic transitions in most compounds. Resistivity measurements show unusual resistivity minima for R = Nd, Sm, Gd, Tb, and Dy, despite the local moment behaviour in these compounds. Hall measurements show anomalous temperature dependences that correspond to the resistivity minima.