國立政治大學應用物理所

演講主題：RD-BZ Hamiltonian in quantum rings
主講人：陳宗緯副教授  中山大學物理系

摘要：

Theoretically, a quantum ring of a circular curve has an

internal Zeeman field, which plays an important role in

spin transport, which manifests the interplay between

the Aharonov-Bohm and Aharonov-Casher topological phases.

We proporse a quantum ring Hamiltonian (RD-BZ Hamiltonian)

that could be used to experimentally detect the existence of the

internal Zeeman field, and thus enable us to change the strength

of the internal Zeeman field. Importantly, we show that the RD-BZ

Hamiltonian can be constructed from the topological insulator.

Similar to the topological insulator, the conductance can exhibit a

quasi plateau near the small spin-orbit coupling. Unlike the topological insulator,

the increase in the strength of the internal Zeeman field would result in a

wider quasi-plateau in conductance, which implies that the ring could remain insulating

state (or conducting state) regardless of the small change in the

spin-orbit coupling. The thermal average of spin and charge currents are

calculated at low temperatures without impurities. We find that the persistent

spin current could be nonzero even when the charge current vanishes at nonzero

magnetic flux. The result suggests a pure spin current in quantum rings, and

its direction can be reversed by changing the magnetic flux. Importantly,

the change in the internal Zeeman field would exhibit the plateau-like pure spin current.

日期：112.10.30(一) 
時間：10:30-12:30
地點：志希樓2F 理學院會議室

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