Elasticity and magnetocaloric effect inMnFe4Si3

The room temperature magnetocaloric material ${\mathrm{MnFe}}₄{\mathrm{Si}}₃$ was investigated with nuclear inelastic scattering (NIS) and resonant ultrasound spectroscopy (RUS) at different temperatures and applied magnetic fields in order to assess the influence of the magnetic transition and the magnetocaloric effect on lattice dynamics. The NIS data give access to phonons with energies above 3 meV, whereas RUS probes the elasticity of the material in the MHz frequency range and thus low-energy, $\ensuremath{\sim}$ neV, phonon modes. A significant influence of the magnetic transition on the lattice dynamics is observed only in the low-energy, long-wavelength limit. ${\mathrm{MnFe}}₄{\mathrm{Si}}₃$ and other compounds in the ${\mathrm{Mn}}_{5\ensuremath{-}\mathrm{x}}{\mathrm{Fe}}_{\mathrm{x}}{\mathrm{Si}}₃$ series were also investigated with vibrating sample magnetometry, resistivity measurements, and M\"ossbauer spectroscopy in order to study the magnetic transitions and to complement the results obtained on the lattice dynamics.