Magneto-optical activity of f–f transitions in ErFe3(BO3)4 and ErAl3(BO3)4 single crystals

Optical spectroscopy of ErFe3(BO3)4: detection of phase transitions and crystal-field levels of the Er3+ ground multiplet

“…According to a single-crystal x-ray structural study of GdFe 3 (BO 3 ) 4 [5], this transition corresponds to the crystal symmetry lowering from the R32 space group to the P3 1 21 one. The first order structural phase transition to lower symmetry occurred in ErFe 3 (BO 3 ) 4 was determined by excess heat capacity in the work [6]. The value T S = 433 K was registered during cooling measurements, and 439 K -during heating measurements.…”

“…The value T S = 433 K was registered during cooling measurements, and 439 K -during heating measurements. Also in the work [6] the research provided absorption, magnetic circular dichroism and natural circular dichroism spectra of ErFe 3 (BO 3 ) 4 as a function of temperature in the range of 90-293 K. As far as we know, there are no other works devoted to the spectroscopic study of ErFe 3 (BO 3 ) 4 single crystals.…”

“…The influence of the phase transition on the spectral lines corresponding to the f-f optical transitions of Er 3+ is difficult to interpret, due to significant broadening of these lines at high temperatures. The difference in the values of T S obtained by different research groups [4,6] is associated with the entrance of impurities from the flux into the crystal in the course of growth, which depends on technology [10]. The powder samples synthesized by the solid-phase synthesis method do not contain such impurities.…”