Pressure-induced effect on electronic excitations in osmium

Electronic Raman scattering has been studied in single crystals of 5d transition metal osmium under pressures up to 60 GPa in the temperature range of 10-300K. With the use of green and blue excitation wavelengths we observe an appearance of well-defined electronic peaks at ∼ 580 cm-1 for wave vector direction q parallel [0001]] and at ∼ 350 cm-1 for q parallel [101-bar 0] in the pressure range of 20-30 GPa. It was shown in our combined experimental and theoretical investigation that a consideration of both a renormalization of the electron self-energies near the Fermi level and a change in the Fermi surface under pressure and temperature variation is needed to describe the observed spectra