Browsing by Author "MacDonald, Allan H."

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Ferminoic Physics in Dipolariton Condensates
(2014-03-17)
Su, Jung-Jung
;
Kim, Na Young
;
Yamamoto, Yoshihisa
;
MacDonald, Allan H.
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電子物理學系
An exciton polariton is an extremely light bosonic quasiparticle that is composed of an exciton and a photon. We report on a theoretical study of exciton-polariton condensation in a system with tunnel-coupled quantum wells. Because their excitons can carry an electric dipole moment, these systems have been referred to as dipolariton condensates. We use a fermionic mean-field theory that can address quantum well and other internal exciton degrees of freedom to describe the new physics present in dipolariton condensates. We find that the role of underlying fermonic degrees of freedom is enhanced and predict that metallic condensates can occur at high carrier densities.
Spatially indirect exciton condensate phases in double bilayer graphene
(2017-01-18)
Su, Jung-Jung
;
MacDonald, Allan H.
;
電子物理學系
;
Department of Electrophysics
We present a theory of spatially indirect exciton condensate states in systems composed of a pair of electrically isolated Bernal graphene bilayers. The ground-state phase diagram in a two-dimensional displacement-field/interbilayer-bias space includes layer-polarized semiconductors, spin-density-wave states, exciton condensates, and states with mixed excitonic and spin order. We find that two different condensate states, distinguished by a chirality index, are stable under different electrical control conditions.