Structural, magnetic, thermodynamic and electrical transport properties of a new compound $\mbox{Pr}_2\mbox{Rh}_{2}\mbox{Ga}$

Abstract

A new ternary intermetallic compound $\mathrm{Pr_2Rh_2Ga}$ was synthesized by arc-melting and was characterized by powder X-ray diffraction (PXRD), magnetization, heat capacity $\mathrm{C}_p(\textit{T})$, and electrical resistivity $\rho(T)$ measurements. PXRD patterns revealed that $\mathrm{Pr_2Rh_2Ga}$ crystallizes in the $\rm{La_2Ni_3}$-type of orthorhombic structure with the space group $Cmca$. The temperature variation of magnetic susceptibility, $\mathrm {C}_p(\textit{T})$ and $\rho(T)$ confirmed that $\mathrm{Pr_2Rh_2Ga}$ exhibits a ferromagnetic behavior with the transition temperature of 18 K. The estimated Sommerfeld coefficient $\gamma$ = 640 mJ/($\mathrm{Pr.mole.K^2}$) from the $\mathrm {C}_p(\textit{T})$ results in the paramagnetic region just above $T_{C}$~was large in comparison to ordinary metals. In the paramagnetic region $\rho(T)$ data showed a metallic behavior characteristic of electron - phonon scattering. The maximum negative magneto-resistance at high field occurs in the region near the magnetic phase transition temperature. The maximum value of magnetic entropy change ($\rm -\Delta \textit{S}_{M}$) and adiabatic temperature change ($\rm \Delta \textit{T}_{ad}$) are $\rm8.2~J/kg.K$ and $\rm3.6~K$, respectively, around the transition temperature for the change of magnetic field 0-9 T. The calculated refrigerant capacity is $\rm70~J/kg$, and $\rm135~J/kg$ for a change of magnetic field 0-5 T and 0-9 T, respectively. Arrott plot derived from isothermal magnetization and the universal scaling plot by normalizing $\rm -\Delta \textit{S}_{M}$ confirm that the compound undergoes a second order ferromagnetic to paramagnetic phase transition.