scholarly journals Optics with Quantum Hall Skyrmions

1998 ◽  
Vol 12 (01) ◽  
pp. 1-35 ◽  
Author(s):  
T. Portengen ◽  
J. R. Chapman ◽  
V. Nikos Nicopoulos ◽  
N. F. Johnson
Keyword(s):  
Optical Properties ◽  
Spin Density ◽  
Theoretical Investigation ◽  
Disordered Systems ◽  
Lower Energy ◽  
Filling Factor ◽  
Electron Gas ◽  
Quantum Hall ◽  
Quantum Hall Systems ◽  
Optical Signature

A novel type of charged excitation, known as a Skyrmion, has recently been discovered in quantum Hall systems with filling factor near ν=1. A Skyrmion — which can be thought of as a topological twist in the spin density of the electron gas — has the same charge as an electron, but a much larger spin. In this review we present a detailed theoretical investigation of the optical properties of Skyrmions. Our results provide means for the optical detection of Skyrmions using photoluminescence (PL) spectroscopy. We first consider the optical properties of Skyrmions in disordered systems. A calculation of the luminescence energy reveals a special optical signature which allows us to distinguish between Skyrmions and ordinary electrons. Two experiments to measure the optical signature are proposed. We then turn to the optical properties of Skyrmions in pure systems. We show that, just like an ordinary electron, a Skyrmion may bind with a hole to form a Skyrmionic exciton. The Skyrmionic exciton can have a lower energy than the ordinary magnetoexciton. The optical signature of Skyrmions is found to be a robust feature of the PL spectrum in both disordered and pure systems.

THEORY OF THE DC MAGNETOTRANSPORT IN LATERALLY MODULATED QUANTUM HALL SYSTEMS NEAR FILLING ν=½

2004 ◽  
Vol 18 (10n11) ◽  
pp. 1581-1594
Author(s):  
NATALYA ZIMBOVSKAYA ◽  
GODFREY GUMBS ◽  
JOSEPH L. BIRMAN
Keyword(s):  
Reasonable Agreement ◽  
Electron Gas ◽  
Quantum Hall ◽  
Dimensional Electron ◽  
One Dimensional ◽  
Quasiclassical Theory ◽  
Quantum Hall Systems ◽  
Analytic Expressions ◽  
Dimensional Electron Gas ◽  
A Current

A quasiclassical theory for DC magnetotransport in a modulated quantum Hall system near filling factor ν=½ is presented. A weak one-dimensional electrostatic potential acts on the two-dimensional electron gas. Closed form analytic expressions are obtained for the resistivity ρ⊥ corresponding to a current at right angles to the direction of the modulation lines as well as a smaller component ρ‖ for a current along the direction of the modulation lines. It is shown that both resistivity components are affected by the presence of the modulation. Numerical results are presented for ρ⊥ and ρ‖ and show reasonable agreement with the results of recent experiments.

scholarly journals Coherence and Disorder in Bilayer Quantum Hall Systems

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
H. A. Fertig ◽  
Ganpathy Murthy
Keyword(s):  
Thin Film ◽  
Finite Temperature ◽  
Filling Factor ◽  
Quantum Hall ◽  
Quantum Fluctuations ◽  
Low Energy ◽  
Quantum Hall Systems ◽  
Low Dissipation ◽  
Bilayer Quantum Hall

The quantum Hall bilayer at total filling factor displays a number of properties akin to superfluidity, most clearly apparent in its very low dissipation in tunneling and counterflow transport. Theoretical descriptions in terms of quantum Hall ferromagnetism or thin-film superfluidity can be developed to explain these phenomena. In either case, merons can be identified as important low energy excitations. We demonstrate that a model in which puddles of merons induced by disorder, separated by narrow regions of interlayer coherence—a coherence network—can naturally explain many of the imperfect superfluid finite temperature properties that are observed in these systems. The periodic realization of this model shows that there can be low energy excitations beyond the superfluid mode. These are associated with transitions between states of different meron number in the puddles, where we argue that merons should be unbound atanytemperature, and which can have important implications for the effect of quantum fluctuations on the system.

scholarly journals ZERO-BIAS CONDUCTANCE ANOMALY IN BILAYER QUANTUM HALL SYSTEMS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 2936-2939
Author(s):  
Y. N. JOGLEKAR ◽  
A. H. MACDONALD
Keyword(s):  
Filling Factor ◽  
Quantum Hall ◽  
Tunneling Conductance ◽  
Coulomb Interactions ◽  
Zero Bias ◽  
Rich Variety ◽  
Quantum Hall Systems ◽  
Zero Bias Conductance ◽  
Quantum Hall System ◽  
Bilayer Quantum Hall

Bilayer quantum Hall system at total filling factor ν=1 shows a rich variety of broken symmetry ground states because of the competition between the interlayer and intralayer Coulomb interactions. When the layers are sufficiently close, a bilayer system develops spontaneous interlayer phase-coherence that manifests itself through a spectacular enhancement of the zero-bias interlayer tunneling conductance. We present a theory of this tunneling conductance anomaly, and show that the zero-bias conductance is proportional to the square of the quasiparticle tunneling amplitude.

SKYRMIONS IN QUANTUM HALL FERROMAGNETS

1999 ◽  
Vol 13 (05n06) ◽  
pp. 461-468 ◽  
Author(s):  
H. A. FERTIG
Keyword(s):  
Close Agreement ◽  
Filling Factor ◽  
Quantum Hall ◽  
Time Dependent ◽  
Square Lattice ◽  
Hartree Fock ◽  
Quantum Hall Systems ◽  
Spin Ordering ◽  
Lattice State ◽  
The Stability

Properties of skyrmions in quantum Hall systems are reviewed. It is shown that, using a Hartree-Fock technique, the size of skyrmions near filling factor ν=1 may be computed, yielding a result in close agreement with experiment. Finite densities of skyrmions are shown to lead to a crystal state with square symmetry due to the spin-dependent nature of their mutual interactions. The square lattice state has an unusual spin ordering which leads to a new gapless mode, analogous to spin waves in a two-dimensional XY antiferromagnet. The stability of the ordered spin state is assessed using a time-dependent Hartree-Fock approach, and a phase diagram is derived which shows the parameter range for which long-range spin ordering is destroyed by quantum fluctuations.

scholarly journals Meron Pseudospin Solutions in Quantum Hall Systems

1998 ◽  
Vol 12 (01) ◽  
pp. 37-48 ◽  
Author(s):  
Sankalpa Ghosh ◽  
R. Rajaraman
Keyword(s):  
Differential Equation ◽  
Filling Factor ◽  
Quantum Hall ◽  
Great Length ◽  
Equation Approach ◽  
Quantum Hall Systems ◽  
Physical Effects ◽  
The Impact ◽  
Bilayer Quantum Hall ◽  
Meron Solution

In this paper we report calculations of some pseudospin textures for bilayer quantum hall systems with filling factor ν=1. The textures we study are isolated single meron solutions. Meron solutions have already been studied at great length by others by minimising the microscopic Hamiltonian between microscopic trial wavefunctions. Our approach is somewhat different. We calculate them by numerically solving the nonlinear integro-differential equations arising from extremisation of the effective action for pseudospin textures. Our results can be viewed as augmenting earlier results and providing a basis for comparison. Our differential equation approach also allow us to dilineate the impact of different physical effects like the pseudospin stiffness and the capacitance energy on the meron solution.

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