Thermal and magnetic properties and optical spectroscopy of SmCr3(BO3)4
We measured the heat capacity, magnetic susceptibility, magnetization, magnetoelectric effect, and optical spectra of samarium chromium borate crystals. It was found that, in SmCr3(BO3)4 single crystals, structures with the space groups R32 and C2/c may coexist. Magnetic phase transitions were discovered at temperatures TN1=7.8±0.5K, TN2=6.7±0.5K, and T3=4.3±0.2K, and assumptions about their nature were made. Based on the high-resolution optical spectra and magnetometry data, the crystal-field parameters in the Sm3+ and Cr3+ positions and the parameters of Cr3+−Cr3+ and Cr3+−Sm3+ exchange interactions were determined. The magnetic properties of the quasi-one-dimensional chromium subsystem were analyzed in the frame of the previously developed self-consistent four-particle cluster model. Despite a strong suppression of Cr3+ magnetic moments by the interchain antiferromagnetic exchange interactions, the contributions of the chromium subsystem to the bulk magnetization are dominant.