Magnetic susceptibility and Verdet constant in rare earth trifluorides

Abstract

On three fluorides CeF₃, NdF₃, and PrF₃ accurate susceptibilities measurements are reported from 2 up to 300 K under a magnetic field applied along the c axis. On the same samples, the optical Faraday rotation has been investigated in the temperature range 8–300 K at 0.6328 μm wavelength in a magnetic field up to 20 kOe. The reciprocal susceptibilities χ⁻¹(T) follow a Curie Weiss law for T>100 K; the observed values of the paramagnetic Curie temperature are − 56 K (PrF₃), − 114 K (CeF₃), and − 26 K (NdF₃). For T77 K. (V and χ are expressed in deg cm⁻¹ Oe⁻¹ and in μ_B mol⁻¹ Oe⁻¹, respectively.) On one hand for NdF₃ and PrF₃, it has been found V/χ =A(1+αT) where A is a constant (−4320 in NdF₃; −7241 in PrF₃); in both samples, α is in the order of −6×10⁻⁴ K⁻¹, note that Faraday rotation measurements performed at 0.4579 and at 0.5017 μm lead to an identical α value. On the other hand in CeF₃, V/χ is a linear function of T⁻¹ and is given by 13700(1+75.9/T).