Magnetic properties of the Pr1-xLaxMnGe system

Magnetization, electrical resistivity, and thermal expansion measurements were carried out on a polycrystalline Pr1-xLaxMnGe system (for x=0.0 endash 0.7) to study its magnetic properties particularly the high magnetic ordering temperature of the Pr sublattice. PrMnGe is known to be antiferromagnetic with TN=415 K. It orders ferromagnetically at 150 K and again becomes antiferromagnetic below 80 K. We have found that the ferromagnetic ordering temperature (T2) and the magnetization decrease with increasing La concentration in Pr1-xLaxMnGe. The low-temperature antiferromagnetic ordering temperature (T1) is also found to decrease with increasing La concentration. The small Pr endash Pr contact distance (which may occur due to a low affinity of lanthanide and Mn elements) is thought to be responsible for the high ordering temperature of Pr moments. Resistivity data have clearly indicated the antiferro- to ferromagnetic (T2) and the ferro- to antiferromagnetic (T1) transitions. Thermal expansivity data suggest the T1 transition to be of first order and the T2 transition to be of second order. copyright 1997 American Institute of Physics