%0 Journal Article
%A Martinez, A.
%A Spottorno Giner, Jorge
%A Figueroa, A.
%A Bartolome, F.
%A Garcia, L. M.
%A Prestipino, C.
%A Hernando Grande, Antonio
%A Crespo del Arco, Patricia
%T Direct measurements of the correlation between reentrant ferromagnetism and lattice expansion in FeCuZr alloys
%D 2010
%@ 1098-0121
%U https://hdl.handle.net/20.500.14352/42610
%X Amorphous metastable alloy of nominal composition [Fe_(0.5)Cu_(0.5)]_(87)Zr_(13) has been synthesized by high-energy ball milling. The alloy exhibit a ferromagnetic behavior with a Curie Temperature of T_(C)=255 K, as determined from low-field measurements whereas no transition to a paramagnetic state is observed under high- enough applied magnetic fields. The evolution of hysteresis loops with temperature as well as thermoremanence measurements indicate an anomalous magnetic behavior characterized by a spontaneous increase in the magnetization values as well as by a magnetic hardening when the temperature is increased above T_(C). These effects are strongly correlated with a dilation of the Fe-Fe nearest-neighbor distances, as determined from extended x-ray absorption fine structure (EXAFS) studies. EXAFS results indicate an almost negligible thermal expansion at temperatures below T_(C) while normal thermal expansion takes place at higher temperatures. Such expansion seems to promote a reinforcement of the ferromagnetic interactions among Fe-Fe atoms that would account for the observed spontaneous increase in the magnetization as well as for the evolution of the coercive field.
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