%0 Journal Article
%A Biniskos, Nikolaos
%A Schmalzl, K.
%A Persson, J.
%A Raymond, S.
%T Paramagnetic fluctuations of the magnetocaloric compound MnFe 4 Si 3
%J Physical review / B
%V 111
%N 5
%@ 2469-9950
%C Woodbury, NY
%I Inst.
%M FZJ-2025-01797
%P 054424
%D 2025
%X An inelastic neutron scattering technique is employed to investigate the paramagnetic spin dynamics in a single-crystalline sample of the magnetocaloric compound MnFe4Si3. In the investigated temperature range, 1.033 x TC to 1.5 x TC , where TC is the Curie temperature, the spin fluctuations are well described by the ferromagnetic Heisenberg model predictions. Apart from the Heisenberg exchange, additional pseudodipolar interactions manifest through a finite long-wavelength relaxation rate that vanishes at the transition temperature (TC = 305 K). Based on the characteristic extent of spin fluctuations in wave-vector and energy space, we determine that the nature of magnetism in MnFe4Si3 is localized above room temperature. This contrasts with the most celebrated Mn- and Fe-based magnetocaloric materials that are considered as itinerant magnets. The field dependence of the paramagnetic spectra shows a strong suppression of the quasielastic excitations, while a field-induced spin-wave mode appears at finite-energy transfers for a magnetic field of 2 T. This modification of the spectra suggests a decrease of magnetic entropy with applied magnetic field that finds echo in the magnetocaloric properties of the system.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:001459360600013
%R 10.1103/PhysRevB.111.054424
%U https://juser.fz-juelich.de/record/1039787