Properties of NaZn_(13)-type LaFe_(13-x)Si_x (x=1.4,1.5) compound with the first-order phase transition

摘要

The Investigacions of dc magnetization, magnetic relaxation, specific heat, and electrical resistance for LaFe_(13-x)Si_x (x= 1.4, 1.5) compounds have been carried out. Obvious thermal and magnetic hysteresis indicates that they experience a first-order phase transition. The phase transition temperature T'_C is driven to high temperature with the increasing of field, which can be described by the relation T'_C(H)~2 -T'_C(0)~2 ∝ H. The large relaxation in magnetization around the field-induced metamagnetic transition field for LaFe_(13-x)Si_x (x = 1.5) can be explained according to the thermal activation theory for the first-order phase transition and fitted by a logarithmic function M(t)/M_0 = 1±Sln(t/t_0+ 1), reflecting the distribution of energy barriers in this sample. The latent heat of LaFe_(13-x)Si_x (x = 1.4) under zero field reaches to 1.8 kJ/kg. A good magnetic-thermal-resistive correspondence is also found in this compound.