Thermal Expansion in Fe₂MAl (M = Ti, V, Cr, Mn, Fe, Co, and Ni) Band Ferromagnets

The linear thermal expansion coefficients (LTEC) of semimetallic Fe₂MAl (M = Ti, V, Cr, Mn, Fe, Co, and Ni) alloys have been measured in the temperature range 80–900 K. The magnetic-fluctuation contribution to LTEC α_m, sf(T) = α_m(T) + α_sf(T) consisting of negative "Stoner" α_m(T) and positive "spin-fluctuation" α_sf(T) contributions. The α_m(T) contribution is assumed to be proportional to the square of the spontaneous magnetization. The α_sf(T) contribution, as is the case in paramagnetic and ferromagnetic states, is due to the effects of inducing local magnetic moments by spin fluctuations.