Crystal growth and magnetic properties of equiatomic CeAl

Abstract

Single crystal of CeAl has been grown by flux method using Ce-Al self-flux. Several needle like single crystals were obtained and the length of the needle corresponds to the [001] crystallographic direction. Powder x-ray diffraction revealed that CeAl crystallizes in orthorhombic CrB-type structure with space group ${Cmcm}$ (no. 63). The magnetic properties have been investigated by means of magnetic susceptibility, isothermal magnetization, electrical transport, and heat capacity measurements. CeAl is found to order antiferromagnetically with a N$\grave{\rm e}$el temperature $T_{\rm N}$ = 10K. The magnetization data below the ordering temperature reveals two metamagentic transitions for fields less than 20kOe. From the inverse magnetic susceptibility an effective moment of $2.66\mu_{\rm B}$/Ce has been estimated, which indicates that Ce is in its trivalent state. Electrical resistivity data clearly shows a sharp drop at 10K due to the reduction of spin disorder scattering of conduction electrons thus confirming the magnetic ordering. The estimated residual resistivity ratio (RRR) is 33, thus indicating a good quality of the single crystal. The bulk nature of the magnetic ordering is also confirmed by heat capacity data. From the Schottky anomaly of the heat capacity we have estimated the crystal field level splitting energies of the $(2J+1)$ degenerate ground state as 25K and 175K respectively for the fist and second excited states.