Emergent Non-Equilibrium Phenomena in Driven Correlated Materials With Strong Spin Orbit Coupling
Technical Report,01 Sep 2014,31 May 2018
University of Texas at Austin Austin United States
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Major Goals The major goal of this project was to theoretically investigate out-of-equilibrium quantum many particle systems that have strong spin-orbit coupling. Particular emphasis was placed on systems with strong correlations. These investigations were carried out with the ultimate aim of finding out-of-equilibrium regimes with interesting properties that might be exploited in applications for the ARO, and DoD more generally. Important progress was made in this direction. Two examples of out-of-equilibrium regimes with interesting properties are Floquet periodically driven systems and pre-thermalized states following a quench to a new Hamiltonian. Both regimes are inherently non-equilibrium and have properties that are quasi-steady state. In a Floquet system, the time averaged over one period properties are independent of time, and in the pre-thermalized state there is a time-window of weak time dependence before the system begins to converge more rapidly to a thermal equilibrium state. In addition to these two scenarios, we also investigated a quench to a Floquet state A system initially in equilibrium is suddenly subjected to a periodic drive. This third scenario is a combination of the first two. It turns out theoretically that one can obtain an approximate time- independent Hamiltonian that describes the dynamics for short-to-intermediate times after the quench to the periodic drive. This observation opens new possibilities for Hamiltonian engineering in solid-state systems, and may allow new physical regimes to be opened, possibly in conventional materials that are well-known and used in existing applications. To this end, we developed a flow equation approach based on renormalization group ideas to obtain such a time-independent effective Hamiltonian.
- Atomic and Molecular Physics and Spectroscopy
- Physical Chemistry