Effects of uniaxial stress on the optical spectrum of DyVO4

Optical absorption spectroscopy is used to investigate the low lying energy levels of DyVO 4 under uniaxial stress and magnetic fields at temperatures above and below the co-operative Jahn-Teller transition. The results agree with the molecular field theory of the previous paper using the parameter σ 0 = 64 ± 4 kg/mm 2 (which represents the stress of e aa − e bb type required to split the ground state energy levels by 27 cm −1 at high temperatures). The behaviour of dilute Dy 3+ in YVO 4 is studied and predicted from the theory. Deviations from the molecular field theory are found and discussed. Comparison of the results with known elastic constants of DyVO 4 indicates that strain coupling dominates the optic mode coupling.