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We have investigated the macroscopic magnetic properties of a magnetocaloric Mn$_{3}$Fe$_{2}$Si$_{3}$ single crystal, which indicate a strong anisotropy. Applying the field perpendicular to c-direction, the magnetic response exhibits two features at T1≈123 K and T2≈69 K, and only one feature in field parallel to c-direction at T2≈ 69 K. Event above T1 the magnetic response is far from Curie-Weiss behavior, indicating the significance of short range magnetic correlations. To elucidate the spin and lattice dynamics in the system, neutron inelastic scattering was carried out on the MERLIN time-of-flight spectrometer [1]. Taking advantage of the repetition rate multiplication (RRM), five separate incident energies (9 meV, 13 meV, 21 meV, 40 and 108 meV) were recorded simultaneously to explore the excitation spectrum in a wide range with adapted resolution conditions. Besides that, the experiment, which provides a complete coverage of large portions of reciprocal space, clearly showed that the magnetic structure of this compound is more complex than previously thought.
[1] R. I. Bewley et al, Physica (Amsterdam) 385B–386B, 1029 (2006).
