Structure and magnetic transport properties of Ge doped La(Co,Si)13 intermetallics

Abstract

The crystal structure and the magnetic and electronic transport properties of Ge doped LaCo10.5Si2.5−xGex (x=0–0.3) intermetallics have been investigated using powder x-ray diffraction and magnetic and electrical measurements. According to the x-ray diffraction pattern analysis, Ge as a dopant decreases the stability of the cubic LaCo 1:13 phase and stabilizes the Si based La(Co,Si) 1:13 tetragonal phase. From the authors’ structural refinement, the authors found that Ge prefers to occupy the 16l(2) position in the tetragonal phase. LaCo10.5Si2.2Ge0.3 shows ferromagnetic order with a metamagnetic state around 350K. An anomaly in resistivity is observed at around 367K, which is associated with the metamagnetic transition. The resistivity follows ρ(T)=ρo+aTn rule in the temperature range of 4–400K with n=1.17(3) for the half metallic state and n=2 for the normal metallic state, respectively. This type of discontinuity can be interpreted as a crossover from a low temperature metamagnetic half metallic state to the normal ferromagnetic-metallic state.