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The quantum spin Hall state is a state of matter proposed to exist in special, two-dimensional semiconductors that have a quantized spin-Hall conductance and a vanishing charge-Hall conductance. The quantum spin Hall state of matter is the cousin of the integer quantum Hall state, and that does not require the application of a large magnetic field.
In 1988, it was proposed that there was a quantum Hall effect without Landau levels. [3] This quantum Hall effect is referred to as the quantum anomalous Hall (QAH) effect. There is also a new concept of the quantum spin Hall effect which is an analogue of the quantum Hall effect, where spin currents flow instead of charge currents. [4]
The spin Hall effect is a transport phenomenon consisting of the appearance of spin accumulation on the lateral surfaces of a sample carrying electric current. The opposing surface boundaries will have spins of opposite sign.
The spin Hall effect consists in the spin accumulation on the lateral boundaries of a current-carrying sample. No magnetic field is needed. It was predicted by Mikhail Dyakonov and V. I. Perel in 1971 and observed experimentally more than 30 years later, both in semiconductors and in metals, at cryogenic as well as at room temperatures.
Zhang was one of the founders of the field of topological insulators. He made one of the first theoretical proposals of the quantum spin Hall effect. Soon after the initial theoretical proposal, his group theoretically predicted the first realistic quantum spin Hall material in HgTe quantum wells. [10]
It is a quantum of a vortex. Semi-Dirac electron: Particle with zero mass gap in one direction of space. electron Surface magnon polariton: Coupling between spin waves and electromagnetic waves. magnon, photon Surface phonon: Vibrational modes in a crystal lattice associated with atomic shifts at the surface. Surface plasmon
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The fan diagram of the composite fermion Landau levels has been determined by transport, and shows both spin-up and spin-down composite fermion Landau levels. [24] The fractional quantum Hall states as well as composite fermion Fermi sea are also partially spin polarized for relatively low magnetic fields. [24] [25] [26]