"Evidence for photo-induced monoclinic metallic VO2 under high pressure "

Wen-Pin Hsieh: Mariano Trigo, David A. Reis, Gianluca Andrea Artioli, Lorenzo Malavasi and Wendy L. Mao; Applied Physics Letters, 01/16/14.

Additional Authors: Mariano Trigo, David A. Reis, Gianluca Andrea Artioli, Lorenzo Malavasi and Wendy L. Mao

Abstract:

We combine ultrafast pump-probe spectroscopy with a diamond-anvil cell to decouple the insulator-metal electronic transition from the lattice symmetry changing structural transition in the archetypal strongly correlated material vanadium dioxide. Coherent phonon spectroscopy enables tracking of the photo-excited phonon vibrational frequencies of the low temperature, monoclinic (M1)-insulating phase that transforms into the metallic, tetragonal rutile structured phase at high temperature or via non-thermal photo-excitations. We find that in contrast with ambient pressure experiments where strong photo-excitation promptly induces the electronic transition along with changes in the lattice symmetry, at high pressure, the coherent phonons of the monoclinic (M1) phase are still clearly observed upon the photo-driven phase transition to a metallic state. These results demonstrate the possibility of synthesizing and studying transient phases under extreme conditions.