Magneto-optical activity and luminescence of f-f transitions in trigonal crystal TmAl3(BO3)4

Abstract Absorption and magnetic circular dichroism (MCD) spectra in the region of the 3H6 → 3H4, 3H6 → 3F3, 3F2, 3H6 → 1G4, 3H6 → 1D2 electron transitions and also luminescence spectrum of the 1D2 → 3F4 transition in Tm3+ ion in the TmAl3(BO3)4 single crystal were measured in the temperature range 95–290 K. Temperature dependences of magneto-optical activity (MOA) of the absorption bands (ratio of the zero moments of MCD and absorption bands) were determined. Mechanisms responsible for MOA of f–f transitions and its temperature dependence in ions with the integer total magnetic moment are analyzed. It is shown that in TmAl3(BO3)4 crystal the temperature-independent paramagnetic effect due to mixing of the electronic states by the magnetic field (so-called B-term) gives the prevailing contribution into MOA of the studied f–f transitions. In contrast to the absorption, luminescence spectrum demonstrates no MOA.