Department of Physics, Center for the Physics of Materials, McGill University, Rutherford Physics Building, 3600 University Street, Montreal, Que., Canada H3A 2T8
Abstract:
Magnetic transitions in La(Fe1?xCox)11.4Si1.6 compounds with x=0–0.08, have been studied by DC magnetic measurements and Mössbauer spectroscopy. The temperature dependence of the Landau coefficients has been derived by fitting the magnetization, M(μ0H), using the Landau expansion of the magnetic free energy. For x0.02 there is a strongly first-order magnetic phase transition between ferromagnetic and paramagnetic (F–P) states in zero external field and a metamagnetic transition from paramagnetic to ferromagnetic (P–F) above Tc. Increasing the cobalt content drives the F–P transition towards second order and eliminates the metamagnetic transition.