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arXiv · 1704.08054

Anomalous lattice dynamics in a sigma-Fe60V40 alloy: Mossbauer spectroscopic study

Stanislaw M. Dubiel·Jan Zukrowski
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Abstract

Lattice dynamics in a sigma-Fe60V40 compound, which shows a re-entrant magnetism and orders ferromagnetic ally at ca. 170K, was investigated with the Mossbauer spectroscopy in the temperature interval of 5-300 K. Two relevant spectral parameters viz. the average center shift, , and the relative recoil-free fraction, f/fo, were explored. The former yielded the Debye temperature, T_D1, and the mean-square velocity of vibration, , while the latter T_D2 and the mean-square amplitude of vibrations, . Significant differences in the lattice-dynamical behaviors in the magnetic and paramagnetic phases were revealed. In particular, the values of T_D were notably lower and those of f/fo greatly higher in the former. This anomalous result has likely its origin in a remarkably high inharmonic contribution to the vibrations found for the ground magnetic state (spin-glass). Especially anomalous behavior vs. temperature exhibits where four well defined ranges could have been identified and ascribed to the paramagnetic, ferromagnetic and two spin-glass phases. Linear correlations between - were found within each of the four ranges. They enabled determination of force constants, hence a change of the potential energy, Ep, in each of the ranges. The total change of Ep=30 meV while the corresponding one of the kinetic energy, determined from the knowledge of , was Ek=21 meV. The lack of balance between Ep and Ek follows from the anharmonic lattice-dynamical behavior observed in the spin-glass state. The results give a strong evidence that magnetism can significantly affect the lattice dynamics.

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Stanislaw M. Dubiel, Jan Zukrowski. 2017-04-26. Anomalous lattice dynamics in a sigma-Fe60V40 alloy: Mossbauer spectroscopic study. https://doi.org/10.1016/j.jmmm.2017.06.038

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