Thermal and magnetic properties and optical spectroscopy of Cr<inf>3</inf> BO<inf>3</inf><inf>4</inf>

Abstract

We measured the heat capacity, magnetic susceptibility, magnetization, magnetoelectric effect, and optical spectra of samarium chromium borate crystals. It was found that, in single crystals, structures with the space groups and may coexist. Magnetic phase transitions were discovered at temperatures , , and , and assumptions about their nature were made. Based on the high-resolution optical spectra and magnetometry data, the crystal-field parameters in the and positions and the parameters of and 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 magnetic moments by the interchain antiferromagnetic exchange interactions, the contributions of the chromium subsystem to the bulk magnetization are dominant.