TY  - JOUR
AU  - Biniskos, Nikolaos
AU  - Schmalzl, K.
AU  - Persson, J.
AU  - Raymond, S.
TI  - Paramagnetic fluctuations of the magnetocaloric compound MnFe 4 Si 3
JO  - Physical review / B
VL  - 111
IS  - 5
SN  - 2469-9950
CY  - Woodbury, NY
PB  - Inst.
M1  - FZJ-2025-01797
SP  - 054424
PY  - 2025
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001459360600013
DO  - DOI:10.1103/PhysRevB.111.054424
UR  - https://juser.fz-juelich.de/record/1039787
ER  -