Negative thermal expansion and itinerant ferromagnetism in Mn$_{1.4}$Fe$_{3.6}$Si$_{3}$

Vikram Singh; R. Nath

doi:10.1063/5.0055695

paper

Negative thermal expansion and itinerant ferromagnetism in Mn $_{1.4}$ Fe $_{3.6}$ Si $_{3}$

arXiv:2107.01245 · doi:10.1063/5.0055695

Abstract

We report the thermal expansion, critical behavior, magnetocaloric effect (MCE), and magnetoresistance ( $M R$ ) on the polycrystalline Mn $_{1.4}$ Fe $_{3.6}$ Si $_{3}$ compound around the ferromagnetic transition. A large negative volume thermal expansion ( $α_{V} \sim - 20 \times 1 0^{- 6}$ K $^{- 1}$ ) is observed across the transition temperature with a strong anisotropic variation of lattice parameters in the $ab$ -plane. The anisotropic magnetoelasticity arises from the competition between magnetic ordering and structural deformation which could be responsible for the large MCE ( $Δ S_{m} ≃ - 6$ J/Kg-K) across the magnetic transition in this compound. The large and negative $M R$ ( $\sim - 3%$ in 80 kOe) is also observed at the transition temperature which can be attributed to the suppression of spin disorder. Further, the Rhodes-Wolfarth ratio (RWR $> 1$ ) and identical field dependence of $M R$ and MCE isotherms indicate the itinerant character of the $3 d$ electrons. The critical exponents determined from the analysis of magnetization and MCE are consistent with the quasi-two-dimensional (2D) Ising model with long range exchange interactions which decays as $J (r) \sim r^{- 3.41}$ . This unconventional quasi-2D Ising character with long-range interactions can be ascribed to strong $ab$ -plane anisotropy and the delocalized $3 d$ electrons in the studied compound.

arXiv comment9 pages, 8 figures, 1 table, J. Appl. Phys. (Accepted)

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Negative thermal expansion and itinerant ferromagnetism in Mn1.4​Fe3.6​Si3​

Abstract

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Cited by in corpus (1)

Negative thermal expansion and itinerant ferromagnetism in Mn $_{1.4}$ Fe $_{3.6}$ Si $_{3}$