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The heat capacity of the Mn3Sn2 compound was measured between 2 and 300 K in magnetic fields up to 7 T. The isothermal magnetic entropy change (ΔSM) and the adiabatic temperature change (ΔTad) were calculated from these data. In agreement with previous magnetic measurements, three transitions are detected in the zero-field heat capacity versus temperature curve, two λ-like peaks close to TC1∼262 K and TC2∼227 K due to ferromagneticlike second-order transitions and a third anomaly at Tt∼197 K ascribed to the development of a weak antiferromagnetic interaction. The Debye temperature is estimated to be ∼303 K from the low-temperature data. The thermal dependences of ΔSM and ΔTad present a two-peak response with peak maxima near TC1 and TC2. For a field variation of 5 T, the values of ΔTad are found to be ∼2.1 and ∼1.6 K, respectively. The results are discussed and compared to previously published data concerning other magnetic refrigerants working near room temperature. [ABSTRACT FROM AUTHOR]

The heat capacity of the [Mn.sub.3][Sn.sub.2] compound is measured in magnetic fields up to 7 T. The isothermal magnetic entropy change and the adiabatic temperature change are calculated and three transitions are detected in the zero-field heat capacity versus temperature curve.

We investigate the magnetic structure of Mn3-xFexSn2 using neutron powder diffraction experiments and electronic structure calculations. These alloys crystallize in the orthorhombic Ni3Sn2 type of structure (Pnma) and comprise two inequivalent sites for the transition metal atoms (4c and 8d) and two Sn sites (4c and 4c). The neutron data show that the substituting Fe atoms predominantly occupy the 4c transition metal site and carry a lower magnetic moment than Mn atoms. Four kinds of magnetic structures are encountered as a function of temperature and composition: two simple ferromagnetic structures (with the magnetic moments pointing along the b or c axis) and two canted ferromagnetic arrangements (with the ferromagnetic component pointing along the b or c axis). Electronic structure calculations results agree well with the low-temperature experimental magnetic moments and canting angles throughout the series. Comparisons between collinear and noncollinear computations show that the canted state is stabilized by a band mechanism through the opening of a hybridization gap. Synchrotron powder diffraction experiments on Mn3Sn2 reveal a weak monoclinic distortion at low temperature (β ~90.08° at 175 K). This lowering of symmetry could explain the stabilization of the c-axis canted ferromagnetic structure, which mixes two orthorhombic magnetic space groups, a circumstance that would otherwise require unusually large high-order terms in the spin Hamiltonian. [ABSTRACT FROM AUTHOR]