Edge states and integer quantum hall effect in topological. Jan 14, 2008 halfinteger quantum hall effect singlelayer graphene. Pdf the integer quantum hall effect is a topological state of quantum matter in two dimensions, and. Pdf edge states and integer quantum hall effect in topological. Majorana quantization and halfinteger thermal quantum hall. Half integer quantum hall effect in high mobility single layer epitaxial. Half integer quantum hall e ect in high mobility single. Madiomanana and john hankinson and mike sprinkle and claire berger and walt a.
Quantum hall effect in graphene with twisted bilayer. In magnetic fields, the emergence of majorana edge current is predicted to manifest itself in the form of halfinteger quantized thermal hall plateau, which has recently been reported for twodimensional honeycomb material. Edge states let us look at the situation in which the sample is only present for y half integer quantum hall effect qhe 2, 3 that is observable even at room temperature in graphene. The unusual quantum hall effect qhe in graphene is described in terms of the composite c bosons, which move with a linear dispersion. The unusual quantum hall effect qhe in graphene is described in terms of the composite c bosons, which move with a linear dispersion relation. Further stability studies of the edge liquid see the figure 4 through.
Energy gaps and a zerofield quantum hall effect in graphene. Levitov1, 1department of physics, massachusetts institute of technology, 77 massachusetts ave, cambridge, massachusetts 029, usa 2department of physics and astronomy, university of manchester, manchester, m 9pl, united. Sep 27, 2009 we suggest realistic ways of creating this quantum state and observing the pseudomagnetic quantum hall effect. Half integer quantum hall effect in high mobility single.
Half integer quantum hall effect in high mobility single layer epitaxial graphene. In this talk, we report a unique bulk half integer qhe observed in a layered dirac semimetal bamnsb 2. Halfinteger quantum hall effect of disordered dirac fermions at a topological insulator surface. The integer quantum hall effect concerns the transport properties of a 2 dimensional electron. Halfinteger quantum hall effect singlelayer graphene. Introduction the unique halfinteger quantum hall effect qhe in monolayer graphene serves as a. International audiencethe quantum hall effect, with a berrys phase of. In the extreme quantum limit, its quantum hall state is accompanied by twodimensional chiral metal at the surface, which represents a novel quantum liquid, never observed in any other bulk single crystal materials 4. Energy gaps and a zerofield quantum hall effect in. We apply a gate voltage, v g, to the silicon substrate to control the charge density in the graphene sample. If time reversal is broken explicitly, for instance by a zeeman field acting on the surface layer, the electromagnetic response of a ti can be described by a half. Half integer quantum hall effect in gatecontrolled epitaxial graphene devices shinichi tanabe, yoshiaki sekine, hiroyuki kageshima, masao nagasey, and hiroki hibino ntt basic research laboratories, nippon telegraph and telephone corporation, 31 morinosatowakamiya, atsugi, kanagawa 2430198, japan. Aps aps march meeting 2020 event meeting calendar aps. The relevance of berrys phase to these experiments is con.
Half integer quantum hall effect in high mobility single layer epitaxial graphene xiaosong wu,1 yike hu,1 ming ruan,1 nerasoa k madiomanana,1 john hankinson,1 mike sprinkle,1 claire berger,1,2 and walt a. We stress that the halfinteger thermal hall conductance in a bulk material is a direct consequence of the chiral majorana edge current. Experiment results the quantum hall effect qhe is one example of a quantum phenomenon that occurs on a truly macroscopic scale. Edge states let us look at the situation in which the sample is only present for y half. Quantum hall effect and topological insulators joint. Nonlinear timereversalsymmetric response, witten effect, and half integer quantum. Peeters1 1departement fysica, universiteit antwerpen groenenborgerlaan 171, b2020 antwerpen, belgium.
This will provide a useful background for our discussion of the quantum hall e ect. Qhe plateaus observed at landau level spectrum with very high cyclotron energy k bilayer novoselov et al, 2005, zhang et al, 2005 manifestation of relativistic dirac electron properties 42x2 spin and valley degeneracy recently. Majorana quantization and halfinteger um hall effect in a. The standard explanations of the famous integer quantized hall plateaus in the transverse resistivity are qualitative, and involve assumptions about disorder, localized states, extended states, edge states, fermi levels pinned by landau levels, etc. Pdf observation of halfinteger quantum hall effect in. Highlyordered wide bandgap materials for quantized anomalous. Integer and halfinteger quantum hall effect in silicene. Integer quantum hall effect, which is the hall effect quantized into integer times e 2 h e. Distinct from this effect, the magnetoelectric coupling would bind a charge e2 in response to a monopole, which is referred to as witten effect.
If time reversal is broken explicitly, for instance by a zeeman field acting on the surface layer, the electromagnetic response of a ti can be described by a halfinteger quantum hall effect of. We stress that the half integer thermal hall conductance in a bulk material is a direct consequence of the chiral majorana edge current. Influence of an external electric field and impurities. The quantum hall effect is an example of a phenomenon having topological features that can be observed in certain materials under harsh and stringent laboratory conditions large magnetic field, near absolute zero temperature. Aps aps march meeting 2020 event halfinteger quantized. The quantum hall effect qhe is one of the most remark able condensedmatter phenomena discovered in the second half of the 20th century, and our talk is. Halfinteger quantum hall effect in gatecontrolled epitaxial graphene devices shinichi tanabe, yoshiaki sekine, hiroyuki kageshima, masao nagasey, and hiroki hibino ntt basic research laboratories, nippon telegraph and telephone corporation, 31 morinosatowakamiya, atsugi, kanagawa 2430198, japan.
It is known that the integer v is the topological invariant of. The quantum hall effect in twodimensional electron gases involves the flow of topologically protected dissipationless charge currents along the edges of a sample. But in highquality twodimensional systems such as gallium arsenide quantum. Quantum hall effect reminder the half integer qhe in graphene energy gaps and splitting of landau levels qhe in pn and pnp junctions spin transport at graphene edge fine structure constant charge impurites in graphene atomic collapse, quasirydberg states nonlinear screening of charge l1 l2 l3. The quantum hall effect in twodimensional electron gases involves the flow of topologically protected dissipationless charge currents along the edges of.
Jul 09, 2018 the fractional quantum hall effect is a variation of the classical hall effect that occurs when a metal is exposed to a magnetic field. Majorana quantization and halfinteger thermal quantum. Dissipative quantum hall effect in graphene near the dirac. In particular, a very unusual halfinteger quantum hall effect and a nonzero berrys phase have been discovered in graphene. Kitaev quantum spin liquid qsl displays the fractionalization of quantum spins into majorana fermions.
It is a simple consequence of the motion of charged particles in a magnetic eld. This causes a gap to open between energy bands, and electrons in the. We report a bulk half integer quantum hall effect in a layered antiferromagnet eumnbi 2, in which fieldcontrollable eu magnetic. Theory of the half integer quantum hall effect in graphene.
Nonlinear timereversalsymmetric response, witten effect, and halfinteger quantum. Quantum hall effect an overview sciencedirect topics. Aps aps march meeting 2020 event surface chiral metal. Half integer quantum hall effect in high mobility single layer epitaxial graphene by xiaosong wu, yike hu, ming ruan, nerasoa k. Basic physics underlying the phenomenon is explained, along with diverse. Pdf integer and halfinteger quantum hall effect in. We report a bulk halfinteger quantum hall effect in a layered antiferromagnet eumnbi 2, in which fieldcontrollable eu magnetic. The graphene charge density obtained from the hall coefficient tempera ture independent is found to be ns1. Pdf half integer quantum hall effect in high mobility. To see this, we can return to the simple definition 1.
Pdf half integer features in the quantum hall effect. We also show that strained superlattices can be used to open significant energy gaps. Quantum hall effect in a bulk antiferromagnet with. Halfinteger quantum hall effect of disordered dirac fermions at a. To incorporate dirac fermions into spintronic applications, their quantum transport phenomena are desired to be manipulated to a large extent by magnetic order in a solid. Jul 11, 2018 the quantum hall effect in twodimensional electron gases involves the flow of topologically protected dissipationless charge currents along the edges of a sample. We discuss experimental data and a new model of the integer quantum hall effect iqhe, which explains an intriguing substructure within landau levels observed at higher currents. To expand potential application of such a distinct quantum. In contrast, for a timereversalsymmetric setup, the signature response is a nonlinear magnetoelectric effect 14, which in the. Quantumhall plateauplateau transition in topgated epitaxial.
Quantum spin hall effect and their topological design of devices. Quantum hall effect reminder the halfinteger qhe in graphene energy gaps and splitting of landau levels qhe in pn and pnp junctions spin transport at graphene edge fine structure constant charge impurites in graphene atomic collapse, quasirydberg states nonlinear screening of charge l1 l2 l3. Quantum spin hall effect and their topological design of. In order experiment was introduced a topological z 2, invariant who characterizes a state as trivial or nontrivial band insulator regardless if the state exhibits or does not exhibit a quantum spin hall effect. The upper inset shows a fourprobe electrical resistance measurement on a monolayer graphene hall bar device lower inset at 1. The fractional quantum hall effect is a variation of the classical hall effect that occurs when a metal is exposed to a magnetic. We study the width of the distinguishable quantumhall plateau to plateau transition.
In particular, a very unusual half integer quantum hall effect and a nonzero berrys phase have been discovered in graphene. In this talk, we report a unique bulk halfinteger qhe observed in a layered dirac semimetal bamnsb 2. Xiaosong wu, yike hu, ming ruan, nerasoa k madiomanana, john hankinson, mike sprinkle, claire berger, walt a. The striking feature of the integer quantum hall effect is the persistence of the quantization i. Huang6, kuang yao chen5, lihung lin7, jauyang wu8, and shengdi lin8 1institute for theoretical physics, university of regensburg, 93040 regensburg, germany 2department of physics, harvard university, cambridge, ma 028, usa. Halfinteger quantum hall effect in graphene exceptionally high mobility graphene samples allow us to investigate transport phenomena in the magnetic quantum limit where the qhe manifests itself. Dissipative quantum hall effect in graphene near the dirac point dmitry a. The fractional quantum hall effect is a variation of the classical hall effect that occurs when a metal is exposed to a magnetic field. Highlyordered wide bandgap materials for quantized. The experiments show inflection points in the hall resistivity around. We suggest realistic ways of creating this quantum state and observing the pseudomagnetic quantum hall effect. Pdf halfinteger quantum hall effect of disordered dirac.
Half integer quantum hall effect of disordered dirac fermions at a topological insulator surface. The discovery of the integer quantum hall effect in twodimensional electron gas opens a window to explore topological phases in quantum matter 1,2. The integer quantum hall effect qhe was discovered by k. After the observation of the halfinteger quantumhall effect for monolayer epitaxial graphene. In contrast to the wellknown integer qhe in silicon mosfets 4 the qhe in graphene occursat halfinteger multiples of 4, the degeneracy due to spin and orbit. Integer and half integer quantum hall effect in silicene. Quantum anomalous hall effect in timereversalsymmetry breaking topological insulators cuizu chang and mingda litopological phases in twodimensional materials. The quantum spin hall phase shares many similarities with the quantum hall effect. In the extreme quantum limit, its quantum hall state is accompanied by twodimensional chiral metal at the surface, which represents a novel quantum liquid, never observed in. Response, witten effect, and halfinteger quantum hall effect heinrichgregor zirnstein,1, bernd rosenow1 1 institut fur theoretische physik, universitat leipzig, d04103 leipzig, germany key words. Indeed, a distinctive halfinteger quantum hall effect has been predicted theoretically, as has the existence of a nonzero berrys phase a geometric quantum.
The quantum hall effect is one of the most important developments in condensed matter physics of the 20th century. However, this is based on the observation of halfinteger quantization. Halfinteger quantum hall effect in gatecontrolled epitaxial. Pdf experimental observation of the quantum hall effect and. More recently, topological insulators have been discovered 4 6, in which topological properties of the bulk wave functions give rise to a topologically. The electron wave packet moves easier in the direction 1 1 0 caxis. The quantum hall effect is referred to as the integer or fractional quantum hall effect depending on whether. Recent experiments based on the proximity effect between a quantum anomalous hall insulator and a conventional superconductor have reported a signature of chiral majorana edge modes he17. In the quantum hall effect the longitudinal conductance vanishes while the hall conductance. Unconventional quantum hall effect in graphene university of. Observation of halfinteger quantum hall effect in singlelayer graphene using pulse magnet article pdf available in journal of the physical society of japan 7711 august 2008 with 78 reads.
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