Anisotropic magnetic properties of light rare-earth diantimonides

Results are presented of anisotropic temperature and field-dependent magnetization $M(H,T)\mathrm{}$ and resistivity $\rho \mathrm{}(H,T)\mathrm{}$ measurements on high quality single crystals of the light rare-earth diantimonides $R{\mathrm{Sb}}_2,$ $R=\mathrm{L}\mathrm{a}-\mathrm{N}\mathrm{d},$ Sm. All of these, excepting ${\mathrm{LaSb}}_2,$ magnetically order at low temperatures, and for ${\mathrm{CeSb}}_2$ and ${\mathrm{NdSb}}_2$ several magnetically ordered phases were observed in low-field magnetization and zero-field resistivity measurements. For $R=\mathrm{C}\mathrm{e}-\mathrm{S}\mathrm{m}$ strong anisotropies, associated with crystalline electric field (CEF) splitting of the $R^{3+}$ ion, were found in $M\left(T\right)\mathrm{}$ measurements both below and above magnetic ordering temperatures. Furthermore, for $R=\mathrm{C}\mathrm{e}-\mathrm{N}\mathrm{d}$ metamagnetic transitions were observed in $M\left(H\right)\mathrm{}$ and $\rho \mathrm{}\left(H\right)\mathrm{}$ for $H\parallel \mathrm{}\left(\mathrm{ab}\right)\mathrm{}$ in the magnetically ordered state. In addition, above 15 kG de Haas–van Alphen oscillations are observed for ${\mathrm{SmSb}}_2$ and Shubnikov–de Haas quantum oscillations are observed above $\sim 120\mathrm{kG}$ for ${\mathrm{NdSb}}_2$ and ${\mathrm{SmSb}}_2.$ The zero-field in-plane resistivity ${\rho }_{\mathrm{ab}}$ of all of the compounds is metallic $(d\rho /dT>\mathrm{}0),$ with residual resistance ratios ranging from 40 to 750. The $c$-axis resistivity is also metallic, but appears to be considerably larger than the in-plane value, consistent with the diantimonides being quasi-two-dimensional materials. The magnetoresistance of all members of the series is large, approximately linear in $H$ at moderate fields, and is also dependent on the relative orientation of the applied magnetic fields to the crystallographic axes. The extreme case of ${\mathrm{SmSb}}_2$ has $\left[\rho \right(55\mathrm{}\mathrm{kG})$$-\rho \mathrm{}\left(0\right)\mathrm{}]/\rho \mathrm{}(0)>50\mathrm{}000\%$ at $T=2\mathrm{}\mathrm{K}$ and $H\parallel c.\mathrm{}$