We predict that the qshe can be observed in an experimentally accessible low temperature regime in silicene with the spin orbit band gap of 1. The search for topological states of matter that do not require magnetic fields for their observation led to the theoretical prediction in 2006 and experimental observation in 2007 of the socalled quantum spin hall effect in hgte quantum wells, a new topological state of quantum matter. Quantum spin hall effect in silicene and twodimensional. Spin hall effect, 2d topological insulator duration. Enhanced spin hall effect by resonant skew scattering in orbitaldependent kondo effect. We further connect the spin current generating spin hall effect to the inverse spin galvanic effect, which often accompanies the she, in which an electrical current induces a nonequilibrium spin. Pdf maxwells equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and. The quantum spin hall effect goteborgs universitet. The integer and fractional quantum hall effects were the first topological states to be. Pdf spin hall effects are a collection of relativistic spinorbit coupling phenomena in which electrical. It is unusual for a puretheory physics paper to make it into the journal science. Here, we report a class of quantum hall effect, the quantum parity hall qph effect, in which boundary channels are distinguished by even or. When the thickness of the quantum well is varied, the electronic state changes from a normal to an inverted type at a critical thickness d c.
Mar 17, 2018 introduction to integer quantum hall effect by ganpathy murthy duration. We use firstprinciples calculations to predict a class of largegap qsh insulators in twodimensional transition metal dichalcogenides with 1t. Basic physics underlying the phenomenon is explained, along with diverse aspects such as the quantum hall effect as the resistance standard. Graphene, the quantum spin hall effect and topological insulators.
The quantum spin hall effect and topological insulators. In the seminal 2dimensional example of the quantum spin hall effect 51, it is related to the existence of spin oriented edge currents, such that each spin component has nonzero conductance. The quantum spin hall effect qshe is observable in twodimensional metals without spin orbit coupling. Quantum spin hall state in monolayer 1twte 2 nature. Quantum hall effect an overview sciencedirect topics. From the dirac equation of an electron in an anisotropic conduction band, the anisotropy of its motion dramatically affects its interaction with applied electric and magnetic fields. Existence of the quantum hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In 1988, it was proposed that there was quantum hall effect without landau levels. Hughes,1 shoucheng zhang1 we show that the quantum spin hall qsh effect, a state of matter with topological properties distinct from those of conventional insulators, can be realized in mercury telluridecadmium. A new 2d electronic phase gapless edge states and transport time reversal symmetry and z 2 topological stability.
The basics are described well but theres nothing about chernsimons theories or the importance of the edge modes. Stanford university with andrei bernevig, taylor hughes. Quantum spin hall effect spin orbit induced energy gap in graphene. Graphene, the quantum spin hall effect and topological insulators i. There are surprisingly few dedicated books on the quantum hall e. We illustrate our findings by analyzing the response of interacting spin chains to a rotating magnetic field. This quantum hall effect is referred to as the quantum anomalous hall qah effect. The quantum hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. An atomic layer of tin in a buckled honeycomb lattice, termed stanene, is a promising largegap twodimensional topological insulator for realizing roomtemperature quantumspinhall effect and therefore has drawn tremendous interest in recent years.
We experimentally and theoretically study artificially enhanced spinorbit coupling in graphene via random. Quantum spin hall effect and topological phase transition in. Because the electronic structures of sn allotropes are sensitive to lattice strain, e. Pdf quantum spin hall effect in electric and magnetic. Quantum anomalous hall quantum spin hall effect in optical superlattices ce shang,1,2,4 xianfeng chen,1,2 weidong luo,3 and fangwei ye1,2, 1the state key laboratory of advanced optical communication systems and networks, school of physics and astronomy. The quantum spin hall effect is a fundamental property of light. Jun 25, 2015 the quantum spin hall effect for electrons allows for the existence of an unusual type of materialcalled a topological insulatorwhich conducts electricity on the surface but not through the. Quantum spin hall effect and their topological design of devices. Concepts like the spin hall effect she69 and birefringent electron optics10 are explored with promising results. Quantum spin hall effect the qsh state can be thought of as b eff two copies of qh states, one for each spin component, each seeing the opposite magnetic field. These edge channels are protected by time reversal symmetry and spin currents propagate without dissipation. Another effect, which demonstrates spin polarized charge transport, is the quantum hall effect qhe. 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.
Quantum spin hall effect and topological phase transition in hgte quantum wells b. Graphenes exceptionally weak spinorbit couplingstemming from carbons low massposes the primary obstacle. Apr 24, 2012 the conventional quantum hall effect is a particular example of the general relation if one views the electric field as a rate of change of the vector potential. Dynamical quantum hall effect in the parameter space pnas. Realization of the quantum spin hall effect in graphene devices has remained an outstanding challenge dating back to the inception of the field of topological insulators. Quantum spin hall qsh effect materials feature edge states that are topologically protected from backscattering. There is also the quantum spin hall effect qshe 5,6, which is characterized by unidirectional edge spin transport, i.
The dimensionality of the zeeman interaction plays an important role in the qshe, and profoundly modifies. The quantum spin hall effect for electrons allows for the existence of an unusual type of materialcalled a topological insulatorwhich conducts. Quantum spin hall effect in twodimensional transition. Three dimensional generalization topological insulator, surface states. Bernevig and zhang, prl, 2006 the qsh state does not break the time reversal symmetry, and can exist without any external magnetic field. Jun 26, 2017 a quantum spin hall qsh insulator is a novel twodimensional quantum state of matter that features quantized hall conductance in the absence of a magnetic field, resulting from topologically. Quantum spin hall effect in twodimensional transition metal. The quantum spin hall effect is a fundamental property of. Quantum spin hall state in monolayer 1twte 2 nature physics. In a twodimensional system the quantum spin hall effect qshe state is characterized by an insulating bulk and two counterpropagating. Evidence for a quantum spin hall phase in graphene decorated. The quantum spin hall effect and topological insulators xiaoliang qi and shoucheng zhang in topological insulators, spinorbit coupling and timereversal symmetry combine to form a novel state of matter predicted to have exotic physical properties. Pdf quantum spin hall effect george rajna academia. The quantum spin hall state is a state of matter proposed to exist in special, twodimensional, semiconductors that have a quantized spin hall conductance and a vanishing charge hall conductance.
Beyond the potential technological applications, the intrinsic spin hall e. Quantum parity hall effect in bernalstacked trilayer. Quantum spin hall effect and topological phase transition. It was shown that hgtebased quantum well structures are the most suitable candidates for its experimental realization. Perspective is also given for recent advances in the quantum hall effect in oxides, narrowgap semiconductors and graphene, as well as a spinoff in physics to anomalous hall effect and spin hall effect. May 21, 2019 the quantum hall effect, which is characterized by an insulating bulk and chiral edge states, has recently been generalized from transport of charges to transport of other degrees of freedom, leading to quantum spin hall and quantum valley hall effects. Dec 15, 2006 we show that the quantum spin hall qsh effect, a state of matter with topological properties distinct from those of conventional insulators, can be realized in mercury telluridecadmium telluride semiconductor quantum wells. The quantum spin hall effect and topological insulators xiaoliang qi is a research associate at the stanford institute for materials and energy science and shoucheng zhang is a professor of physics at stanford university in stanford, california. In a twodimensional system the quantum spin hall effect qshe state is characterized by an insulating bulk and two counterpropagating helical edge states. In order experiment was introduced a topological z 2, invariant who characterizes a state as trivial or nontrivial band insulator regardless if the state.
Introduction to integer quantum hall effect by ganpathy murthy duration. Pdf quantum renormalization of the spin hall effect t. A quantum spin hall qsh insulator is a novel twodimensional quantum state of matter that features quantized hall conductance in the. Recently, a new class of topological states has emerged, called quantum spin hall qsh states or topological insulators see physics today, january 2008, page 19. Advanced condensed matter physics iitg 4,470 views. Dec 12, 2014 quantum spin hall qsh effect materials feature edge states that are topologically protected from backscattering. 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. The quantum spin hall effect is a unique phase of matter in which the bulk of the material is an insulator, but topological quantum states exist at the. In the new study, researchers bring together one of physics most venerable set of equations those of james clerks. Graphene and the quantum spin hall effect upenn physics. In two dimensions the helical edge states give rise to the quantum spin hall qsh effect, in the absence of any external magnetic field. Mele department of physics and astronomy, university of pennsylvania, philadelphia, pennsylvania 19104, usa received 22 june 2005. Z2 topological order and the quantum spin hall effect. The quantum spin hall phase shares many similarities with the quantum hall effect.
1069 730 287 671 1467 820 50 826 846 1411 973 1228 279 882 146 1147 979 1066 828 1567 304 1166 697 401 281 237 686 556 1240