Spin currents in a coherent exciton gas

• Published in: Physical review letters Vol. 110; no. 24; p. 246403
• Main Authors: High, A A, Hammack, A T, Leonard, J R, Yang, Sen, Butov, L V, Ostatnický, T, Vladimirova, M, Kavokin, A V, Liew, T C H, Campman, K L, Gossard, A C
• Format: Journal Article
• Language: English
• Published: United States American Physical Society 11-06-2013
• Subjects: Condensed Matter; Mesoscopic Systems and Quantum Hall Effect; Physics
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.110.246403

We report the observation of spin currents in a coherent gas of indirect excitons. The realized long-range spin currents originate from the formation of a coherent gas of bosonic pairs--a new mechanism to suppress the spin relaxation. The spin currents result in the appearance of a variety of polarization patterns, including helical patterns, four-leaf patterns, spiral patterns, bell patterns, and periodic patterns. We demonstrate control of the spin currents by a magnetic field. We also present a theory of coherent exciton spin transport that describes the observed exciton polarization patterns and indicates the trajectories of the spin currents.