Irreversible electronic transition with possible metallization in Y3Fe5O12 at high pressure

Abstract

The effect of high pressure up to 70 GPa on the optical absorption spectra in yttrium iron garnet Y3Fe5O12 single crystals was studied in diamond anvil cells. In the pressure range 40–50 GPa, an electronic transition with a drastic narrowing in the optical gap from ∼2.3 eV to nearly zero was observed, implying possible metallization. The final narrowing of the optical gap to zero is extrapolated at about 55 GPa. It is shown that the phase transition in yttrium iron garnet observed at 40–55 GPa is possibly a transition of the insulator-metal type. At decompression, the backtransition to the insulating state is not completely reversible. The final spectrum at ambient pressure is substantially different from the initial one and corresponds to an optical gap of about 1.8 eV, while, in the initial state, the gap value is ∼2.6 eV.