Magnetoresistance in LaFe11.2Co0.7Si1.1 compound

Magnetoresistance has been studied in LaFe_11.2Co_0.7Si_1.1 compound. The ferromagnetic ordering at Curie temperature T_C of 274 K was found being accompanied by a drastic negative lattice expansion due to the strong structural and magnetic interplay. Such a simultaneous magnetic and lattice change would cause changes in transport properties. The measured transport properties indicate that the transition can be induced by temperature or applied magnetic field. The sample shows a metallic character below T_C, whereas the electrical resistance decreases dramatically and then recovers the metal-like behavior above T_C. Application of a magnetic field retains the transitions via increasing the ferromagnetic ordering temperature. An isothermal increase of field leads to an increase of resistance at temperatures near but above T_C, which is a result of the field-induced metamagnetic transition from paramagnetic to ferromagnetic state.