Anisotropic magnetic properties and giant magnetocaloric effect of single-crystal PrSi

A single crystal of PrSi was grown by the Czochralski method in a tetra-arc furnace. Powder x-ray diffraction of the as-grown crystal revealed that PrSi crystallizes in an FeB-type structure with space group Pnma (No. 62). The anisotropic magnetic properties were investigated by means of magnetic susceptibility, isothermal magnetization, electrical transport, and heat capacity measurements. Magnetic susceptibility data clearly indicate the ferromagnetic transition in PrSi with a ${T}_{C}$ of 52 K. The relative easy axis of magnetization was found to be the [010] direction. Heat capacity data confirm the bulk nature of the transition at 52 K and exhibit a huge anomaly at the transition. A sharp rise in the low-temperature heat capacity has been observed (below 5 K) which is attributed to the ${}^{141}$Pr nuclear Schottky heat capacity arising from the hyperfine field of the Pr moment. The estimated Pr magnetic moment 2.88 ${\ensuremath{\mu}}_{\mathrm{B}}$/Pr from the hyperfine splitting is in agreement with the saturation magnetization value obtained from the magnetization data measured at 2 K. From the crystal electric field analysis of the magnetic susceptibility, magnetization, and heat capacity data it is found that the degenerate $J=4$ Hund's rule derived state of the Pr${}^{3+}$ ion splits into nine singlets with an overall splitting of 284 K, the first excited singlet state separated by just 9 K from the ground state. The magnetic ordering in PrGe appears to be due to the exchange-generated admixture of low-lying crystal field levels. The magnetocaloric effect (MCE) has been investigated from magnetization data along all three principal crystallographic directions. The large magnetic entropy change, $\ensuremath{-}\ensuremath{\Delta}{S}_{M}=$22.2 J/kg K, and the relative cooling power, RCP = 460 J/kg, characteristic of the giant magnetocaloric effect are achieved near the transition temperature (${T}_{C}$ = 52 K) for $H=$ 70 kOe along $[010]$. Furthermore, the PrSi single crystal exhibits a giant MCE anisotropy.