Mesoscopic Transport in Electrostatically Defined Spin-Full Channels in Quantum Hall Ferromagnets

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Spintronics

Background:

• Quantum Hall effect (QHE) transitions in magnetic semiconductor heterostructures are crucial for fundamental physics.
• Domain walls (DWs) in these systems arise from the hybridization of counterpropagating edge states with opposite spin polarization.
• Understanding electron transport through DWs is key to exploring novel quantum phenomena.

Purpose of the Study:

• To investigate electron transport through individual, electrostatically controlled domain walls (DWs) in CdMnTe quantum wells.
• To characterize the nature and transport properties of helical DWs.
• To explore the potential of DWs for future quantum technologies.

Main Methods:

• Utilizing electrostatic control to induce and position DWs in CdMnTe quantum wells.
• Measuring electron transport properties across individual DWs under varying magnetic fields.
• Comparing experimental data with a theoretical model of transport through spin-orbit induced gap states.

Main Results:

• Conduction through DWs exhibits symmetry under magnetic field reversal, confirming their helical nature.
• Long DWs behave as insulators with localization lengths of 4-6 μm.
• Shorter DWs show resistance saturation at low temperatures, with mesoscopic fluctuations observed.
• A theoretical model accurately describes transport through impurity states within the spin-orbit induced gap.

Conclusions:

• Helical DWs possess the necessary symmetry for forming synthetic p-wave superconductors.
• Electrostatic control of single helical DWs is a significant step towards reconfigurable networks and braiding non-Abelian excitations.
• This work paves the way for novel quantum devices based on controlled domain wall dynamics.