Tunable dispersion of the edge states in the integer quantum Hall effect

Abstract

Topological aspects represent currently a boosting area in condensed matter physics. Yet there are very few suggestions for technical applications of topological phenomena. Still, the most important is the calibration of resistance standards by means of the integer quantum Hall effect. We propose modifications of samples displaying the integer quantum Hall effect which render the tunability of the Fermi velocity possible by external control parameters such as gate voltages. In this way, so far unexplored possibilities arise to realize devices such as tunable delay lines and interferometers.

Tunable Signal Velocity in the Integer Quantum Hall Effect of Tailored Graphene

“…The non-linear spacing between the LL results from the relativistic behavior of the electrons near the Dirac points. The magnetic length plays the same role as in the IQHE in the 2DEG 10,27 . It sets the scale for the diameter of the circular motion of the electrons due to the Lorentz force.…”

“…Thus, it suggested itself to use the well-established IQHE for the same purpose. Indeed, it is possible to obtain tunable signal velocities in two-dimensional electron gases (2DEG) subjected to a perpendicular magnetic field 10 . Still, there are challenges opposing an immediate realization: modifying the edges by periodically aligned bays with the required precision on small length scales of 100 nm represents a tremendous task to sample design.…”

Topological magnetic excitations

“…Clearly, this requires spatial resolution so that the boundaries can be excited separately. Furthermore, temporal resolution is required to measure velocities of signal transmission along the edges which constitutes a key quantity of edge modes [156][157][158]. Then, control and manipulation of topological magnonic systems can be envisaged which will trigger a new boost to the field.…”

“…2, can reduce this velocity by hybridizing propagating edge modes with local, non-dispersive modes in the attached bays. For electronic systems this has been studied thoroughly for topological systems with chiral edge modes [156][157][158]. Adjusting the single-ion anisotropy [166] in order to change the dispersion is a promising route.…”

Delocalization of edge states in topological phases

“…The application of the integer quantum Hall effect in high-precision metrology stands out [15]. Another interesting suggestions are tunable group velocities of edge states to realize delay lines and interference devices [16,17].…”