Magnetic anisotropy in HoIr${}_2$Si${}_2$ ($I4/mmm$)

Abstract

Single crystals of HoIr${}_2$Si${}_2$ with the body-centered ThCr${}_2$Si${}_2$-type structure ($I4/mmm$) were grown by Bridgman method from indium flux. Single crystal structure determination yielded a Si-z position of 0.378(1) in the structure. We excluded the presence of the high temperature phase with the primitive CaBe${}_2$Ge${}_2$-type structure ($P4/nmm$) by powder X-ray diffraction. Magnetic measurements on the single crystals yield a Neel temperature of $T_{\mathrm{N}}=22\mathrm{K}$. In the inverse magnetic susceptibility a strong anisotropy with Weiss temperatures ${\Theta }_W^{001}=26\mathrm{K}$ and ${\Theta }_W^{100}=-26\mathrm{K}$ occurs above $T_{\mathrm{N}}$. The effective magnetic moment ${\mu }_{\mathrm{eff}}^{001}=10.64{\mu }_B$ and ${\mu }_{\mathrm{eff}}^{100}=10.53{\mu }_B$ is close to the expected value for a free Ho${}^{3+}$ ion, ${\mu }_{\mathrm{eff}}^{calc}=10.6{\mu }_B$. The field dependent magnetization shows a step-like behaviour due to crystalline electric field effects.