Aharonov–Bohm interference of fractional quantum Hall edge modes

We measure the magneto-conductance through a micron-sized quantum dot hosting about 500 electrons in the quantum Hall regime. In the Coulomb blockade, when the island is weakly coupled to source and drain contacts, edge reconstruction at filling factors between one and two in the dot leads to the formation of two compressible regions tunnel coupled via an incompressible region of filling factor ν = 1. We interpret the resulting conductance pattern in terms of a phase diagram of stable charge in the two compressible regions. Increasing the coupling of the dot to source and drain, we realize a Fabry-Pérot quantum Hall interferometer, which shows an interference pattern strikingly similar to the phase diagram in the Coulomb blockade regime. We interpret this experimental finding using an empirical model adapted from the Coulomb blockaded to the interferometer case. The model allows us to relate the observed abrupt jumps of the Fabry-Pérot interferometer phase to a change in the number of bulk quasiparticles. This opens up an avenue for the investigation of phase shifts due to (fractional) charge redistributions in future experiments on similar devices. :1910.12525v1 [cond-mat.mes-hall] arXiv

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“…In previous experiments, gating potentials and capacitances of similar samples were optimized in such a way [27,30,33,34].…”

Section: Methodsmentioning

confidence: 99%

“…1(c)]. Thereby we operate the device as a quantum Hall interferometer [18,27,42,45,49]. This is achieved using V LB = −0.86 V and V RB = −1.43 V [c.f.…”

Section: Interferometermentioning

confidence: 99%

Observation of quantum Hall interferometer phase jumps due to a change in the number of bulk quasiparticles

et al. 2020

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“…Geometrical or dimensional constraints can promote the formation of new quantum phases which are absent in bulk systems. Prominent examples include metallic surface states in topological insulators 1 , superconducting vortex state below the Kosterlitz-Thouless transition 2 , interface-induced 2D electron gas 3 and superconductivity [4][5][6] , integer and fractional quantum Hall edge states [7][8][9] and Wigner crystals 10,11 in systems with reduced dimensions. Geometrical constraints on the nano-to mesoscale are usually enforced by design in quantum dots, nanowires, thin films, heterostructures, metamaterials, etc.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host

et al. 2020

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We report a magnetic state in GaV 4 Se 8 which emerges exclusively in samples with mesoscale polar domains and not in polar monodomain crystals. It is manifested by a sharp anomaly in the magnetic susceptibility and the magnetic torque, distinct from other anomalies observed also in polar mono-domain samples upon transitions between the cycloidal, the Néel-type skyrmion lattice and the ferromagnetic states. We ascribe this additional transition to the transformation of distinct magnetic textures, confined to polar domain walls (DW), to the ferromagnetic (FM) state. The emergence of these DW-confined magnetic states is likely driven by the mismatch of different spin spirals, hosted by the adjacent domains. A clear anomaly in the magneto-current indicates that the DWconfined magnetic states also have strong contributions to the magnetoelectric response. We expect polar DWs to commonly host such confined magnetic edge states and, thus, offer a fertile ground to explore novel forms of magnetism.

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“…One plausible reason for the observed crossover with increasing filling factor is the velocity-dependent phase coherence of the edge states 49 . The velocity, hence the phase coherence of the edge states, increases with a higher filling factor, as the confining potential becomes steeper.…”

Section: Discussionmentioning

confidence: 99%

Interplay of filling fraction and coherence in symmetry broken graphene p-n junction

et al. 2020

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Graphene p–n junction (PNJ) with co-propagating spin-valley polarized quantum Hall (QH) edges is a promising platform for studying electron interferometry. Though several conductance measurements have been attempted for such PNJs, the edge dynamics of the spin-valley symmetry broken edge states remain unexplored. In this work, we present the measurements of conductance together with shot noise, an ideal tool to unravel the dynamics, at low temperature, in a dual graphite gated hexagonal boron nitride encapsulated high mobility graphene device. The conductance data show that the symmetry broken QH edges at the PNJ follow spin selective equilibration. The shot noise results as a function of both p and n side filling factors reveal the unique dependence of the scattering mechanism. Remarkably, the scattering is found to be fully tunable from incoherent to coherent regime with the increasing number of QH edges at the PNJ, shedding crucial insights of edge dynamics.

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Aharonov–Bohm interference of fractional quantum Hall edge modes

Cited by 106 publications

References 55 publications

Observation of quantum Hall interferometer phase jumps due to a change in the number of bulk quasiparticles

Observation of quantum Hall interferometer phase jumps due to a change in the number of bulk quasiparticles

Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host

Interplay of filling fraction and coherence in symmetry broken graphene p-n junction

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