Magnetic Properties of Quasi-One-Dimensional Lanthanide Calcium Oxyborates CaO(BO).

This study examines the lanthanide calcium oxyborates CaO(BO) ( = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb). The reported monoclinic structure (space group ) was confirmed using powder X-ray diffraction. The magnetic ions are situated in well-separated chains parallel to the axis in a quasi-one-dimensional array. Here we report the first bulk magnetic characterization of CaO(BO) using magnetic susceptibility χ() and isothermal magnetization () measurements at ≥ 2 K. With the sole exception of CaTbO(BO), which displays a transition at = 3.6 K, no magnetic transitions occur above 2 K, and Curie-Weiss analysis indicates antiferromagnetic nearest-neighbor interactions for all samples. Calculation of the magnetic entropy change indicates that CaGdO(BO) and CaHoO(BO) are viable magnetocaloric materials at liquid helium temperatures in the high-field and low-field regimes, respectively.