Magnetic, resonance, and optical properties of Cu3Sm(SeO3)2 O2Cl: A rare-earth francisite compound

In this combined experimental and theoretical paper, we study the properties of Cu3Sm(SeO3)2O2Cl belonging to the francisite family of compounds, which are novel frustrated layered compounds. Cu3Sm(SeO3)2O2Cl is synthesized through a solid state reaction. Characterizations through measurements of magnetization, specific heat, X-band electron spin resonance, and rare-earth optical spectroscopy, establish that the compound orders antiferromagnetically at TN=35K and undergoes a spin-reorientation phase transition at TC=8.5K due to the interplay of anisotropies in transition metal and rare-earth subsystems. The ground state Kramers doublet of Sm is found to split only at T<TC when the exchange field is aligned along the nonzero component of its g factor. Prior to full saturation with Ms≤3μB/f.u., which is reached under application of moderate magnetic field, the magnetization is found to exhibit complicated hysteresis behavior related to field-induced metamagnetic phase transitions. The first principles calculations reveal the hierarchy of exchange interaction parameters in the kagome-type magnetic subsystem of Cu3Sm(SeO3)2O2Cl.