Experimental Definition of Zeeman Splitting of Excited States of Tb3+ Ion in Y3Al5O12

Abstract

The energy spectrum of the 7F3 multiplet of a Tb3+ ion in one of the non‐equivalent positions (of D2 symmetry) occupied by a rare‐earth ion in the Y3Al5O12 crystallographic garnet structure is calculated. The energy spectrum of the 7F3 state is characterized by the presence of quasi‐doublet states formed by closely located Stark singlet states, that are effectively “mixed” in an external magnet field H. This inference is seriously confirmed by results of experimental studies of magnetopolarized luminescence on the radiative 5D4 → 7F3 4f–4f transition in Y3Al5O12:Tb3+. The optical transitions are identified, and the components of the g‐factor of the 7F3(Γ2, Γ4) quasi‐doublets in the Y3Al5O12 structure are determined.

Features of Circularly Polarized Luminescence of the Paramagnetic Garnets Y3Al5O12:Tb3+ and Y3Al5O12:Ho3+ in Magnetic Field

“…An analogous difference in the spectra I AE is observed at T ¼ 90 K for line 4 (18345 cm À1 ), not shown in Fig. At the same time, the spectral dependence of the MCPL degree for line 4 exhibits analogous dependence and is shifted from zero (the line center) by the value of the "paramagnetic" substitution (the C 0 member of MCPL [1,6]) which is defined by the Zeeman splitting of thermally occupied "mixed" states of the quasi-doublet from which a radiative "quasi-doublet-quasi-doublet" transition occurs. As far as line 1 (18439 cm À1 ) is concerned, at T ¼ 90 K (as at room temperature) its orthogonal circularly polarized components remain equal in intensity and are shifted relative to each other in energy by approximately 2.4 cm À1 at H ¼ 4.5 kOe.…”

“…At the same time, for line 3 (18395 cm À1 ) the difference in the intensities I þ and I À becomes observable only at low temperature. The possibility of such an identification is confirmed by the specific linear spectral behavior of the MCPL degree within the emission line 1 (becoming zero at the line center), characteristic of the A 0 member of MCPL [1,6]. 1.…”

“…For the data obtained at T ¼ 90 K it is distinctly seen that line 2 in the magnetic field has a doublet structure (while its Zeeman splitting is insignificant) and that the magnetic field has a great impact on the intensities I þ and I À of the long-wavelength component of the doublet (see Fig. 1 (2002) Taking into account the specific behavior of dispersion and the temperature dependence of the A 0 and C 0 members of MCPL of a non-Kramers ion [6] (see Fig. At the same time, for line 3 (18395 cm À1 ) the difference in the intensities I þ and I À becomes observable only at low temperature.…”

“…The spectra of circularly polarized luminescence in magnetic field and the spectra of the degree P of magnetic circularly polarized luminescence (MCPL), connected with the 5 D 4 ! The degree of MPL, P ¼ ðI þ À I À Þ=ðI þ þ I À Þ, was measured with a highly sensitive differential technique of polarization modulation of secondary radiation by a piezo-optical modulator [6][7][8]. 5 I 8 transitions of the Ho 3þ ions (17930-18560 cm À1 ) [11] in the YAG garnet structure were studied.…”

“…Moreover, "mixing" (in the external magnetic field) of other closely located states of a magneto-active ion in the optical transition can result in a temperature-independent difference in oscillator strengths of orthogonal circularly polarized components of a corresponding luminescence line. It is known that the Van Fleck mechanism of "mixing", in the magnetic field, of non-degenerate electronic states of the non-Kramers Tb 3þ and Ho 3þ ions plays a specific role both in the formation of anisotropic magnetic properties [4,5] and in the considerable magneto-optical activity (MOA) of the radiative 4f-4f transitions in crystals with these ions [6,7]. 4 I 15=2 [3].…”