Theoretical Physics Seminar:
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Mar 05, 2009 11:00 AM, Theoretical Physics Seminar Room, LC 3.17
Spin-currents, self-induced magnetism, and fractional flux quanta: adventures with triplet Josephson junctions
Speaker: Brydon, Philip
Abstract: The study of Josephson junctions involving unconventional superconductors is of major interest for both technological and basic-science purposes. Recently, interest has turned to the (as yet unrealized) possibility of constructing Josephson junctions from triplet superconductors such as Sr_2RuO_4. In such systems, the novel spin degree of freedom of the triplet Cooper pair allows the possibility of a number of exotic Josephson effects. Chief among these is the possibility of a Josephson spin current, which can be produced in two basic ways: through the geometric mis-alignment of the vector order parameters (d-vectors) of the two superconductors, or the use of a magnetically-active tunneling barrier. These two mechanisms can be combined in a remarkable synthesis: the mis-alignment of the d-vectors on either side of a non-magnetic tunneling barrier breaks time-reversal symmetry, which permits the appearance of a spontaneous magnetization of the tunneling barrier. This radically alters the properties of the junction, with the appearance fractional flux quanta.
