Magneto‐optical properties of RbMnF₃ in the paramagnetic state

The spectrum of the Faraday effect (FE) in the range of 9000 to 37000 cm⁻¹ and its temperature dependence in the range of 90 to 570 K are investigated in RbMnF₃. The absorption spectrum in the range of 19000 to 60000 cm⁻¹ and the magnetic circular dichroism spectrum in the range of 19000 to 36000 cm⁻¹ are also obtained at room temperature. FE is decomposed to the following components: A₀, the frequency‐independent FE, A, the diamagnetic FE, and C, the temperature‐dependent paramagnetic FE which are found to be commensurate in value with each other. It is shown that: 1. the paramagnetic magneto‐optical activity for the majority of d—d transitions in RbMnF₃ is close to the maximum possible one in spite of the lack of orbital moment in the ground state of the Mn²⁺ ion and due to the spin—orbit interaction in the excited states; 2. C, the term of FE is caused by the highest frequency d—d transition ⁶A_1g → ⁴T_2g(⁴F) at ω = 51000 cm⁻¹; 3. the diamagnetic FE is caused by the wide band of strong absorption at ω > 60000 cm⁻¹.