Double magnetic phase transitions and magnetotransport anomalies in a new compound Gd${}_{\text{2}}$AgSi${}_{\text{3}}$

Abstract

Dc and ac-magnetic susceptibility ($\chi$), specific heat ($C_{\mathrm{P}}$), electrical resistivity ($\rho$) and magnetoresistance measurements performed on the new polycrystalline compound $\mathrm{G}{\mathrm{d}}_2\mathrm{AgS}{\mathrm{i}}_3$, crystallizing in the $\alpha$-$\mathrm{ThS}{\mathrm{i}}_2$ tetragonal structure, are reported. Two magnetic phase transitions were observed in dc and ac susceptibility, specific heat, and resistivity measurements at temperatures ${\mathrm{T}}_{{\mathrm{N}}_1}=11$ K and ${\mathrm{T}}_{{\mathrm{N}}_2}=20$ K, despite a single site occupied by Gd atom, which is an indication of the complex magnetic behavior. $\mathrm{G}{\mathrm{d}}_2\mathrm{AgS}{\mathrm{i}}_3$ turns out to 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 ${\mathrm{T}}_{{\mathrm{N}}_2}$), mimicking the behavior of exotic $\mathrm{G}{\mathrm{d}}_2\mathrm{PdS}{\mathrm{i}}_3$, in this ternary family. The isothermal magnetic entropy and adiabatic temperature changes reach a value of 9.5 J/kg-K and 7.5 K respectively for the field change of 9 T.

6 pages, 8 figures