Double magnetic phase transitions and magnetotransport anomalies in a new compound Gd2AgSi3

Abstract Dc and ac – magnetic susceptibility (χ), specific heat ( C P ), electrical resistivity (ρ) and magnetoresistance measurements performed on the new polycrystalline compound Gd 2 AgSi 3 , crystallizing in the α – ThSi 2 tetragonal structure, are reported. Two magnetic phase transitions were observed in dc and ac susceptibility, specific heat and resistivity measurements at temperatures T N 1 = 11 K and T N 2 = 20 K, despite a single site occupied by Gd atom, which is an indication of the complex magnetic behavior. Gd 2 AgSi 3 turns out be one of the rare Gd compound in which a minimum is observed in the temperature dependence of resistivity in the paramagnetic state and also negative magnetoresistance over a wide temperature range (above T N 2 ), mimicking the behavior of exotic Gd 2 PdSi 3 , in this ternary family. The isothermal magnetic entropy change, adiabatic temperature change, and refrigerant capacity reach a value of 9.5 J/kg-K, 7.5 K and 302 J/kg, respectively for the change of magnetic field 0-9 T.