Ultrafast Spectroscopy of Strongly Correlated Systems Dynamics of the Insulator-Metal Transition

Speaker: Elsa Abreu

When: October 23, 2013 (Wed), 03:30PM to 04:30PM (add to my calendar)
Location: PRB 365

This event is part of the Departmental Seminars.

Dissertation committee:

Richard Averitt, Shyam Erramilli, Claudio Chamon, Kevin Smith, Robert Carey Elsa

Abstract Metal-insulator transitions (MITs) are a striking manifestation of the interactions between the various degrees of freedom in complex materials. Under certain conditions of temperature, doping, pressure or photoexcitation a material can change one or several of its electronic, structural, spin or orbital arrangements and undergo a MIT. Such transitions can be probed statically or dynamically, through ultrafast snapshots of the material’s properties following a specific, controlled excitation. Photoinduced phase transitions are an ideal path to study the dynamical behavior of the different degrees of freedom as well as their individual contribution to the alterations in the material’s macroscopic response and to the timescale on which these alterations occur. Typical examples of MITs are those of vanadium dioxide (VO2) and vanadium sesquioxide (V2O3), which in bulk and at atmospheric pressure occur at 340K (VO2) and 160K (V2O3). This talk focuses on the investigation of the dynamics of the insulator to metal transition in single crystalline thin films of V2O3 following optical or far infrared excitation. Conductivity dynamics induced ¬by an ultrafast photoexcitation enable the understanding of the mechanism of nucleation and growth that eventually gives rise to the metallic state in V2O3. These results will be put in the context of past and future studies of transition metal oxides using optical and far infrared spectroscopies, with an emphasis on the developing field of nonlinear THz spectroscopy.