Investigation of a spin transition in a LaCoO$_{3}$ single crystal by the method of X-ray magnetic circular dichroism at the cobalt $K$- and $L_{2,3}$-edges

Spin transitions of cobalt ions in LaCoO$_{3}$ single crystals have been studied by the method of X-ray magnetic circular dichroism (XMCD) at the $K$- and $L_{2,3}$-edges of Co$^{3+}$ ions. The orbital momentum of cobalt ions obtained for the $K$-edge at the 3 $d$ level in the region of the spin transition in the temperature range from 25 to 120 K increases by a factor of approximately 1.6, whereas the slope of the magnetization curve value in the same temperature range and magnetic field increases by a factor of more than 10. XMCD experiments at the cobalt $L_{2,3}$-edges demonstrate gradual growth of the ratio of the orbital momentum to the spin one $L/S$ from 0.48 to 0.53 in the temperature range from 60 K to 120 K.