High-Resolution Spectroscopy of the ErCrO3 Crystal: A New Phase Transition?

Infrared absorption spectra of the ErCrO3 crystal in the region of transitions in the Er3+ ion are f- f recorded for the first time. An analysis of high-resolution temperature-dependent spectra reveals a step at T' = 47 K on the temperature dependences of the characteristics of spectral lines, in addition to the features at temperatures of magnetic ordering T-N = 133 K and spin-reorientation transition T-SR = 9.3 K. This feature can be associated with either a previously unknown phase transition or with local changes in the crystal struc-ture. The shape of the lines at liquid helium temperatures indicates the presence of additional positions for Er3+ ions in the ErCrO3 crystal. Presumably, these are positions near uncontrolled impurities that enter the crystal during its growth by the solution-melt method and form regions with a distorted structure responsible for the occurrence of polarization.