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. Theory and experiment markus konig1, hartmut buhmann1, laurens w. What is an intuitive explanation of the quantum hall effect. Thus an atomicscale system was shown to have intrinsically quantum properties. The quantum world forced itself upon us when physicists tried and failed to explain the results of experiments using the tools of classical. Quantum spin hall effect and tunable spin transport in as. Starting from this year, the spin hall effect attracted a lot of attention because.
The quantum hall effect springer series in solidstate. Pdf the spin hall effect originates from the coupling of the charge and spin currents. The quantum hall effect graduate texts in contemporary. The quantum spin hall effect goteborgs universitet. It was shown that hgtebased quantum well structures are the most suitable candidates for its experimental realization. Why this paper is important importance of quantum spin hall effect. Hughes2, chaoxing liu3,2, xiaoliang qi2 and shoucheng zhang2 1physikalisches institut ep iii, universitat wu. In the new study, researchers bring together one of physics most venerable set of equations those of james clerks maxwells famous theory of light with one of the hot. A relativistic version of the quantum spin hall effect was introduced in the 1990s for the numerical simulation of chiral gauge theories. This paper fills the missing piece giving a real world. The realization of quantum spin hall effect in hgte quantum wells is considered a milestone. The spin hall effect, whereby flowing particles experience orthogonally directed, spindependent lorentzlike forces, is observed in a quantumdegenerate gas and used to produce a coldatom spin.
These edge channels are protected by time reversal symmetry and spin currents propagate without dissipation. The fractional quantum hall effect, in particular, has opened up a new paradigm in the study of strongly correlated electrons, and it has been shown that new concepts, such as fractional statistics, anyon, chiral luttinger liquid and composite particles, are. Quantum spin hall effect figure from science 301, 48 2003 the number of edge channels in the sample is directly related to the value of the quantum hall conductance figure from physics today feb 2010. In the presence of a strong magnetic field, charged particles confined to move in the plane can form a series of new states of matter with bizarre properties.
Three experiments that show quantum physics is real. The quantum anomalous hall effect is defined as a quantized hall effect realized in a system without an external magnetic field. Quantum spin hall effect and their topological design of devices. By analogy with the quantum spinhall effect of electrons, spinmomentum locking phenomena can also be found in photonic topological insulators 7,8,9,10,11. Integer and fractional quantum hall effects in lattice. The search for topologically nontrivial states of matter has become an important goal for condensed matter physics. A recent test has confirmed the predictions of quantum trajectory theory. In order experiment was introduced a topological z 2, invariant who characterizes a state as trivial or.
Quantum spin hall effect and their topological design of. Petr kratochvilpublic domain in a paper that crystalizes knowledge from a. The basics are described well but theres nothing about chernsimons theories or the importance of the edge modes. The classical hall voltage current flow pattern in a hall bar how to solve discovery of the quantum hall the role of mobility the 2deg in a mosfet setting up the quantum mechanical hamiltonian effective masses etc oscillation of the fermi level, landau levels group velocity of the eigenstates channels from a contact to another. In this talk, i shall discuss the theory and experiment of the qah. Complex effects in condensedmatter systems can often find analogs in cleaner optical systems. Our work on the quantum spin hall qsh effect is motivated both by the quest. Further stability studies of the edge liquid see the figure 4 through which conduction takes place. Existence of the quantum hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. Voltage drop is measured to see whether the conductance becomes zero or not.
Phenomenology of the quantum spin hall effect one key element that was instrumental in arriving at the theoretical prediction of the qsh state is the prediction of the intrinsic spin hall sh effect in doped semiconductors 15, 16. Spielman joint quantum institute, national institute of standards and technology and department of physics, university of maryland, gaithersburg, md 20899, usa introduction to. The spinorbit coupling thus leads to an accumulation of electrons with different spins on opposite sides of the sample. Unexpected edge conduction in mercury telluride quantum wells. In two dimensions the helical edge states give rise to the quantum. Quantum spin hall effect and topological phase transition. Theory and experiment article in journal of the physical society of japan 773 january 2008 with 156 reads how we measure reads. There are surprisingly few dedicated books on the quantum hall e. A quantum spin hall system possesses a pair of helical edge states. Work supported in part by us department of energy contract deac0276sf00515. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Mele department of physics and astronomy, university of pennsylvania, philadelphia, pennsylvania 19104, usa received 22 june 2005. Tunable spin transport in nanodevices is highly desirable to spintronics. First experimental observation of the inverse spin hall effect 14. As an experimentalist, one must combine a public lecture with an. 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. The quantum spin hall effect is a fundamental property of light 25 june 2015 credit. The existence of the quantum hall effect requires breaking of the. The quantum hall effects remains one of the most important subjects to have emerged in condensed matter physics over the past 20 years. In this work, we combine transport and microwave impedance. Quantum spin hall effect it is unusual for a puretheory physics paper to make it into the journal science. 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.
Spielman joint quantum institute, national institute of standards and technology and department of physics, university of maryland, gaithersburg, md 20899, usa introduction to spin hall effect w. Quantum hall effect 55 skipping cyclotron orbits fourterminal sample configuration to measure the hall and longitudinal resistivities quantum hall effect 56 for a given plateau not a perfect conductor. Jul, 2006 report of an electrical demonstration of the spin hall effect using highquality metallic devices that incorporate a ferromagnet and a tunnel junction to inject spin polarized electrons. Direct electronic measurement of the spin hall effect nature. The unexpected discovery of the quantum hall effect was the result of. Quantum spin hall effect figure from science 301, 48 2003 the number of edge channels in the sample is directly. Provides new physics and new devices previously published work. Quantum hall effects an introduction 1 quantum hall effects an introduction m. Levitov department of physics, massachusetts institute of technology, 77 massachusetts ave, cambridge, ma 029 electron edge states in graphene in the quantum hall e. Andrei bernevig and shoucheng zhang department of physics, stanford university, stanford, california 94305, usa received 18 april 2005.
Namely, the description via a semiclassical boltzmann like theory 3240,42 and the calculation based on the quantum mechanical kubostreda formula 41,43,44. The quantum spin hall effect and topological insulators. Quantum spin hall effect and topological phase transition in hgte quantum wells. The second half of this volume is concerned with the theory of and experiments on the many body problem posed by fractional effect. Theory of the fractional quantum hall effect in graphene. Jan 26, 2015 if you have a 2d confined electron system at very low temperature below the fermi state and affected by a strong magnetic field 10 t. Quantum spin hall effect in inverted typeii semiconductors. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. May 31, 2011 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 exhibits or does not exhibit a quantum spin hall effect. Why does the sterngerlach quantum spin experiment conflict. Google and ibm clash over milestone quantum computing experiment. It exhibits the quantum spin hall effect, in which an electric current can induce a transverse spin current or spin accumulation near the system boundary.
Two prominent ones are prange and girvin, \the quantum hall e ect this is a collection of articles by most of the main players circa 1990. Topologically distinct from all other known states of matter, including qh states, qsh states have been theoretically predicted and experimentally observed in mercury telluride quantum wells, 2,3 2. This article is within the scope of wikiproject physics, a collaborative effort to improve the coverage of physics on wikipedia. In this work, we predict a quantized spin hall effect in the absence of any magnetic field, where the intrinsic spin hall conductance is quantized. Hughes, chaoxing liu, xiaoliang qi, shoucheng zhang download pdf. View the table of contents for this issue, or go to the journal homepage for more. Despite jains obvious bias towards promoting his own perspective, i think this book remains the best introduction to the physics of the quantum hall effect. Start this article has been rated as startclass on the projects quality scale. Recently, a new class of topological insulators has been proposed.
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. So aspect did a third experiment, published in 1982, adding a. Jan 07, 2008 the search for topologically nontrivial states of matter has become an important goal for condensed matter physics. The quantum hall effect graduate texts in contemporary physics.
Quantum spin hall effect and topological phase transition in. Ppt quantum hall effects an introduction powerpoint. Institute of fundamental and frontier sciences, university of electronic science and technology of china, chengdu 610054, china department of materials science and engineering, university. 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. Interpreting recent experimental results of light interactions with matter shows that the classical maxwell theory of light has intrinsic quantum spin hall effect properties even in free space. The quantum spin hall state is a state of matter proposed to exist in special, twodimensional, semiconductors that have a quantized spinhall conductance and a vanishing chargehall conductance. Diagonal long range order in the lowest landau level 44 viii.
No amount of examination of newtons laws as an abstract system will lead you to quantum mechanics. The sh effect can be thought of as the spin counterpart to the classical charge hall effect. In recent years, the quantum anomalous hall effect was proposed theoretically and realized experimentally. Hall effect can in principle exist in band insulators, where the spin current can flow without dissipation. The quantum spin hall phase shares many similarities with the quantum hall effect. Here, we predict existence of quantum spin hall effects and tunable spin transport in asgraphane, based on firstprinciple density functional theory and tight binding calculations. In a twodimensional system the quantum spin hall effect qshe state is characterized by an insulating bulk and two counterpropagating helical edge states. If you have a 2d confined electron system at very low temperature below the fermi state and affected by a strong magnetic field 10 t. Specific unsolved problems are mentioned throughout the book and a. A landauginzburg theory for paired quantum hall states 41 c.
The spin hall effect, whereby flowing particles experience orthogonally directed, spin dependent lorentzlike forces, is observed in a quantum degenerate gas and used to produce a coldatom spin. This effect is known as the classical spin hall effect, and quantum mechanics adds a dramatic twist on top. Two prominent ones are prange and girvin, the quantum hall e. Spin hall effect 6, 7 and the dirac cone surface states of three dimensional. Jun 26, 2015 interpreting recent experimental results of light interactions with matter shows that the classical maxwell theory of light has intrinsic quantum spin hall effect properties even in free space. Qhe 2, exciton condensation in bilayer quantum hall systems 3, the quantum spin hall effect. The sterngerlach experiment demonstrated that the spatial orientation of angular momentum is quantized. So the stern gerlach experiment is evidence that the magnetic moment of electrons in atoms, and thus electron spin, is quantized, because the results resemble the second case above, not the first.
Quantum phase transitions, as we shall see, are present in a number of quantum hall e. High this article has been rated as highimportance on. Why those proposed real world examples are unrealistic importance of this paper. The quantum spin hall effect is a fundamental property of. There are surprisingly few dedicated books on the quantum hall e ect. The quantum hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Fortunately, our understanding of this menagerie is based almost entirely on many body wavefunctions of a rather simple form.
Report of an electrical demonstration of the spin hall effect using highquality metallic devices that incorporate a ferromagnet and a tunnel junction to inject spinpolarized electrons. Quantum spin hall qsh theory predicts that when the thickness of an hgte. The calculation of this parameter should be the objective of a microscopic theory. In the original experiment, silver atoms were sent through a spatially varying magnetic field, which deflected them before they struck a detector screen, such as a glass slide. Quantum spin hall effect in a twoorbital model on a honeycomb lattice. At finite t, the two peaks widen and merge due to thermal spin fluctuations. Z2 topological order and the quantum spin hall effect. Bernevig and zhang, prl, 2006 the qsh state does not break the time reversal symmetry, and can exist without any external magnetic field. In these devices, the quantum spin hall effect can be used as a spin current injector and detector for the metallic spin hall effect, and vice versa, allowing for an allelectrical detection of.
The quantum anomalous hall effect is a novel manifestation of topological structure in manyelectron systems and may have potential applications in future electronic devices. Motivated by this suggestion, researchers have proposed the quantum spin hall qsh effect for graphene 7aswellasfor semiconductors 8, 9, where the spin current is carried entirely by the helical edge states in twodimensional samples. Pdf since electrons have an internal degree of freedom, spin, they are characterized not only. The initial direction of the magnetic moment of the electron is limited by quantization of spin.
The fractional quantum hall effect is one of the most remarkable phenomena in all of condensed matter physics. What the previously proposed real world examples are. The quantum spin hall effect is a fundamental property of light. Monolayer asgraphane is constituted by using as adsorbing on graphane with honeycomb h vacancies. Spin polarization of the quantum spin hall edge states. In two dimensions the helical edge states give rise to the quantum spin hall qsh effect, in the absence of any external magnetic field.