Monday, February 23, 20151:30 PM - 2:30 PMCNLS Conference Room (TA-3, Bldg 1690)|
From Equilibrium to Non-Equilibrium Spin Systems: Making waves on the Fermi sea.
Kevin S. BedellBoston College
The first experimental realization of Bose-Einstein condensation (BEC) in an ultra-cold atomic Bose gas was about two decades ago. Some years later ultra-cold atomic Fermi gases were discovered. The excitement here started to “heat up” when it was discovered that the interaction strength could be tuned due to the proximity of a Feshbach resonance. With this tunable interaction it is possible to study these Fermi gases from weak to strong coupling while approaching the unitary limit of the interactions. For example, at unitarity the Fermi gas 6Li has achieved a BCS superfluid transition temperature of, TC/TF ~ 0.17. This high temperature superfluid has attracted much attention with speculations that this system may be a model for strongly interacting systems from high temperature superconductors to a quark-gluon plasma that could be produced in heavy ion collisions. With the additional ability to control the spin populations in these cold Fermi gases non-equilibrium transport properties, like spin diffusion, have also been studied in these systems; opening up the possibility of new insights into spin transport in spintronic devices. Spin transport in spintronic devices is mostly studied in the high temperature “classical regime” but we are proposing to look at the low temperature “quantum regime” because the physics of spin transport changes dramatically in the non-equilibrium state of even the simplest of the devices, F/N, where F is a ferromagnetic metal and N is a normal metal. What I will show in my talk is that the underlying physics connecting the ultra-cold Fermi gases and non-equilibrium transport in spintronic devices is the Fermi liquid theory for equilibrium and non-equilibrium spin systems; supplemented with a “simple yet elegant” microscopic model for the interactions.
Host: Robert Ecke