Synthesis, structure and properties of RNiBN (R = rare-earth elements)

We report the structural and physical properties of new nitridoborates RNiBN (R = Nd, Sm, Gd, Tb, Dy, Ho, and Er). These compounds crystallize in a tetragonal LaNiBN-type structure with two-dimensional Ni2B2 and RN layers. The physical properties measurements indicate that they are antiferromagnetic metals. For R = Gd and Ho, a successive magnetic transition was observed below N e ' el temperature, possibly associated with spin reorientation due to Ruderman-Kittel-Kasuya-Yosida interaction. A giant magnetocaloric effect was measured in the R = Er and Ho compounds, which is related to a field-induced first-order metamagnetic transition from antiferromagnetic to ferromagnetic state. Our results indicate that RNiBN (R = Er and Ho) may be promising candidates for low temperature magnetic refrigeration