Interrelation between lattice vibration and magnetic state in structural and magnetic transitions of γMnNi alloy

Abstract

Electrical resistivities of antiferromagnetic γMn-17.0 and 18.7 at.%Ni alloys were measured at temperatures from 300 to 520 K in magnetic fields from 0 to 0.23 Wb/m 2. Based on the measured resistivities, change in magnetic states of the alloys when the structural and the magnetic transitions took place were studied. It was observed that the magnetic states at these temperatures showed strong temperature dependence as expected for an itinerant electron antiferromagnet dominated by spin density fluctuation of itinerant 3d-electrons. However, magnetic changes as if in a localized spin magnet were observed in temperature ranges of the transitions. In order to study these complicated magnetic changes, the measured total resistivities in the temperature ranges were separated into two terms of lattice resistivity and magnetic resistivity. It was determined from the study of these two terms, that localized magnetic moment at the lattice site can be large enough to change the lattice vibration. The lattice vibration and the spin fluctuation show complementary change to each other with an increase in the field and show different amplitude of change by the field for each transition. Based on these results, the complicated magnetic changes and interrelation between the lattice vibration and the spin fluctuation in the structural and the magnetic transitions are studied.