EPR in LiHoF 4 with a far infrared laser

Abstract

A low-temperature FIR spectrometer was used for measuring EPR of LiHoF 4 in the field range 0–7 T, frequency range 150–1600 GHz. Zero field splittings and g-values for the lowest four energy levels are presented. Two sets of hyperfine lines were observed, corresponding to Δ m N = 0 and Δ m N = −1, each set with line spacings according to A h = 1.57 GHz . The exchange part of the molecular field constant is determined and compared to results from previous experiments.