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arXiv · 2408.03808

Paramagnetic fluctuations of the magnetocaloric compound MnFe$_4$Si$_3$

N. Biniskos·K. Schmalzl·J. Persson·S. Raymond
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Abstract

Inelastic neutron scattering technique is employed to investigate the paramagnetic spin dynamics in a single crystalline sample of the magnetocaloric compound MnFe$_4$Si$_3$. In the investigated temperature range, 1.033$\times T_{C}$ to 1.5$\times T_{C}$, where $T_C$ is the Curie temperature, the spin fluctuations are well described by the ferromagnetic Heisenberg model predictions. Apart from the Heisenberg exchange, additional pseudo-dipolar interactions manifest through a finite long-wavelength relaxation rate that vanishes at the transition temperature ($T_C = 305$\,K). Based on the characteristic extend of spin fluctuations in wave-vector and energy space we determine that the nature of magnetism in MnFe$_4$Si$_3$ is localized above room temperature. This contrasts with the most celebrated Mn and Fe based magnetocaloric materials that are considered as itinerant magnets.

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N. Biniskos, K. Schmalzl, J. Persson, S. Raymond. 2024-08-07. Paramagnetic fluctuations of the magnetocaloric compound MnFe$_4$Si$_3$. https://doi.org/10.1103/physrevb.111.054424

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