Images of Edge Current inInAs/GaSbQuantum Wells

Abstract

Quantum spin Hall devices with edges much longer than several microns do not display ballistic transport: that is, their measured conductances are much less than e 2 /h per edge. We imaged edge currents in InAs/GaSb quantum wells with long edges and determined an effective edge resistance. Surprisingly, although the effective edge resistance is much greater than h/e 2 , it is independent of temperature up to 30 K within experimental resolution. Known candidate scattering mechanisms do not explain our observation of an effective edge resistance that is large yet temperature-independent.

Bosonic edge states in gapped honeycomb lattices

“…The appearance of an edge state is the consequence of the non-trivial topological properties of the bulk band. Edge states have been created in various systems such as quantum wells and graphene [5][6][7][8]; the existence of edge states constitutes a central motivation for studying these kinds of materials. Edge states are perfectly conducting channels and play an important role in electronic transport [9].…”

Visualizing ferromagnetic domains in magnetic topological insulators

“…18 The anomalous hall resistivity reaches the predicted quantized value of h/e 2 , demonstrating the existence of a dissipationless chiral conducting channel at the sample edge when the system is in single domain state. In multi-domain state, chiral edge states propagate at magnetic domain walls, 5 allowing direct observation of the chiral edge channel, e.g., utilizing scanning probe microscopies, [19][20][21] without a physical edge. In a ferromagnet, multi-domain state forms spontaneously to minimize magneto-static energy.…”

Partial hybridisation of electron-hole states in an InAs/GaSb double quantum well heterostructure

“…By altering the tunnel barrier thickness, one can then effectively change the coupling between the two carrier gases. Several studies also report altering the composition of the coupled quantum well system in order to make the contribution from the topologically protected edge states more distinct from residual the bulk conductivity when the system is tuned into a state where the 2DTI behaviour dominates transport 6,10,11 . However, as these studies use the magnitude of the resistance resonance at charge neutrality as a measure of quality 10,11 , it is possible that the coupling between the two carrier gases is adversely affected.…”

“…Two materials systems have been experimentally verified as 2DTIs to date, HgTe quantum wells 3,4 and InAs/GaSb coupled quantum wells 5,6,7 . In both of these structures the non-trivial topology is provided by so-called inverted band structures.…”