Paramagnetic fluctuations of the magnetocaloric compound MnFe4Si3

IF 3.7 2区物理与天体物理 Q1 Physics and Astronomy

Physical Review B Pub Date : 2025-02-18 DOI:10.1103/physrevb.111.054424

N. Biniskos, K. Schmalzl, J. Persson, S. Raymond

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Abstract

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×TC to 1.5×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.

Published by the American Physical Society

2025

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来源期刊

Physical Review B 物理-物理：凝聚态物理

CiteScore

6.70

自引率

32.40%

发文量

审稿时长

3.0 months

期刊介绍： Physical Review B (PRB) is the world’s largest dedicated physics journal, publishing approximately 100 new, high-quality papers each week. The most highly cited journal in condensed matter physics, PRB provides outstanding depth and breadth of coverage, combined with unrivaled context and background for ongoing research by scientists worldwide. PRB covers the full range of condensed matter, materials physics, and related subfields, including: -Structure and phase transitions -Ferroelectrics and multiferroics -Disordered systems and alloys -Magnetism -Superconductivity -Electronic structure, photonics, and metamaterials -Semiconductors and mesoscopic systems -Surfaces, nanoscience, and two-dimensional materials -Topological states of matter