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. Influence of an external electric field and impurities. It is known that the integer v is the topological invariant of. Aps aps march meeting 2020 event surface chiral metal. Halfinteger quantum hall effect singlelayer graphene. Half integer quantum hall effect in high mobility single layer epitaxial graphene by xiaosong wu, yike hu, ming ruan, nerasoa k. Aoki, in comprehensive semiconductor science and technology, 2011. 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 is referred to as the integer or fractional quantum hall effect depending on whether. Quantum anomalous hall effect in timereversalsymmetry breaking topological insulators cuizu chang and mingda litopological phases in twodimensional materials. Aps aps march meeting 2020 event halfinteger quantized. 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. Pdf the integer quantum hall effect is a topological state of quantum matter in two dimensions, and. Peeters1 1departement fysica, universiteit antwerpen groenenborgerlaan 171, b2020 antwerpen, belgium.
It is a simple consequence of the motion of charged particles in a magnetic eld. We report a bulk half integer quantum hall effect in a layered antiferromagnet eumnbi 2, in which fieldcontrollable eu magnetic. The striking feature of the integer quantum hall effect is the persistence of the quantization i. Quantum spin hall effect and their topological design of. Further stability studies of the edge liquid see the figure 4 through. Quantum hall effect in graphene with twisted bilayer. We study the width of the distinguishable quantumhall plateau to plateau transition. The quantum hall effect in twodimensional electron gases involves the flow of topologically protected dissipationless charge currents along the edges of. The electron wave packet moves easier in the direction 1 1 0 caxis.
Nonlinear timereversalsymmetric response, witten effect, and halfinteger quantum. Quantum hall effect in a bulk antiferromagnet with. The fractional quantum hall effect is a variation of the classical hall effect that occurs when a metal is exposed to a magnetic. But in highquality twodimensional systems such as gallium arsenide quantum. The unusual quantum hall effect qhe in graphene is described in terms of the composite c bosons, which move with a linear dispersion. Pdf integer and halfinteger quantum hall effect in. Aps aps march meeting 2020 event meeting calendar aps. 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. 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.
Integer and half integer quantum hall effect in silicene. Xiaosong wu, yike hu, ming ruan, nerasoa k madiomanana, john hankinson, mike sprinkle, claire berger, walt a. 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 um hall effect in a. Edge states let us look at the situation in which the sample is only present for y half. Energy gaps and a zerofield quantum hall effect in graphene. In particular, a very unusual half integer 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.
We report a bulk halfinteger quantum hall effect in a layered antiferromagnet eumnbi 2, in which fieldcontrollable eu magnetic. The unusuallylarge landau level spacing makes qhe in graphene observable. Madiomanana and john hankinson and mike sprinkle and claire berger and walt a. Experiment results the quantum hall effect qhe is one example of a quantum phenomenon that occurs on a truly macroscopic scale. Half integer quantum hall effect in high mobility single layer epitaxial. Theory of the half integer quantum hall effect in graphene. The graphene charge density obtained from the hall coefficient tempera ture independent is found to be ns1. Highlyordered wide bandgap materials for quantized anomalous. The discovery of the integer quantum hall effect in twodimensional electron gas opens a window to explore topological phases in quantum matter 1,2. 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. Quantum hall effect an overview sciencedirect topics. 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. Halfinteger quantum hall effect of disordered dirac fermions at a topological insulator surface.
We apply a gate voltage, v g, to the silicon substrate to control the charge density in the graphene sample. Half integer quantum hall e ect in high mobility single layer. The upper inset shows a fourprobe electrical resistance measurement on a monolayer graphene hall bar device lower inset at 1. The integer quantum hall effect qhe was discovered by k. Pdf edge states and integer quantum hall effect in topological. International audiencethe quantum hall effect, with a berrys phase of. Pdf halfinteger quantum hall effect of disordered dirac. 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. More recently, the quantum anomalous hall effect was observed for the surface dirac state in magnetic topological insulator thin films 5, 6. The fractional quantum hall effect is a variation of the classical hall effect that occurs when a metal is exposed to a magnetic field. 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. The quantum hall effect in twodimensional electron gases involves the flow of topologically protected dissipationless charge currents along the edges of a sample. More recently, topological insulators have been discovered 4 6, in which topological properties of the bulk wave functions give rise to a topologically. 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.
Integer quantum hall effect, which is the hall effect quantized into integer times e 2 h e. We suggest realistic ways of creating this quantum state and observing the pseudomagnetic quantum hall effect. 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. 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.
After the observation of the halfinteger quantumhall effect for monolayer epitaxial graphene. Halfinteger quantum hall effect in gatecontrolled epitaxial. 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. Sep 27, 2009 we suggest realistic ways of creating this quantum state and observing the pseudomagnetic quantum hall effect. Majorana quantization and halfinteger thermal quantum hall. Edge states and integer quantum hall effect in topological.
Pdf half integer quantum hall effect in high mobility. 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. 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. Dissipative quantum hall effect in graphene near the dirac. The unusual quantum hall effect qhe in graphene is described in terms of the composite c bosons, which move with a linear dispersion relation.
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. Unconventional quantum hall effect in graphene university of. This will provide a useful background for our discussion of the quantum hall e ect. Indeed, a distinctive halfinteger quantum hall effect has been predicted theoretically, as has the existence of a nonzero berrys phase a geometric quantum. Quantum hall effect and topological insulators joint. 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. In the quantum hall effect the longitudinal conductance vanishes while the hall conductance. Nonlinear timereversalsymmetric response, witten effect, and half integer quantum.
Pdf half integer features in the quantum hall effect. The original, classical hall e ect was discovered in 1879 by edwin hall. Energy gaps and a zerofield quantum hall effect in. Pdf experimental observation of the quantum hall effect and. Jan 14, 2008 halfinteger quantum hall effect singlelayer graphene. In particular, a very unusual halfinteger quantum hall effect and a nonzero berrys phase have been discovered in graphene. Dissipative quantum hall effect in graphene near the dirac point dmitry a. The integer quantum hall effect concerns the transport properties of a 2 dimensional electron. In this talk, we report a unique bulk halfinteger qhe observed in a layered dirac semimetal bamnsb 2. Half integer quantum hall effect of disordered dirac fermions at a topological insulator surface. In this talk, we report a unique bulk half integer qhe observed in a layered dirac semimetal bamnsb 2.
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. The quantum spin hall phase shares many similarities with the quantum hall effect. Integer and halfinteger quantum hall effect in silicene. The quantum hall effect is one of the most important developments in condensed matter physics of the 20th century.
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. Theory of the halfinteger quantum hall effect in graphene. Halfinteger quantum hall effect of disordered dirac fermions at a. Basic physics underlying the phenomenon is explained. 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. Pdf observation of halfinteger quantum hall effect in. To see this, we can return to the simple definition 1. Half integer quantum hall effect in high mobility single. We also show that strained superlattices can be used to open significant energy gaps. Highlyordered wide bandgap materials for quantized. We stress that the halfinteger thermal hall conductance in a bulk material is a direct consequence of the chiral majorana edge current. This causes a gap to open between energy bands, and electrons in the. The experiments show inflection points in the hall resistivity around.
Distinct from this effect, the magnetoelectric coupling would bind a charge e2 in response to a monopole, which is referred to as witten effect. 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. Half integer quantum hall effect in high mobility single layer epitaxial graphene. 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. 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. 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. In contrast, for a timereversalsymmetric setup, the signature response is a nonlinear magnetoelectric effect 14, which in the. Introduction the unique halfinteger quantum hall effect qhe in monolayer graphene serves as a. We stress that the half integer thermal hall conductance in a bulk material is a direct consequence of the chiral majorana edge current. Quantumhall plateauplateau transition in topgated epitaxial. 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 thermal quantum. However, this is based on the observation of halfinteger quantization.