Oxford Physics



Magneto-optics & Transport

 
 

1. Magneto-Transport



We are studying the magnetotransport properties of several different semiconductor systems looking at:



  • Superlattice transport in InAs/GaSb superlattices.


    • These materials have a broken (crossed) band gap alignment which leads to new superlattice properties. We have recently observed strong Stark Cylotron resonances where the magnetic quantum energy is equal to the energy drop across one period of the superlattice.

  • Magnetophonon Effects
    • Resonant scattering occurs when the separation between magnetic quantum levels (Landau levels) is equal to phonon energies. This gives information on the scattering processes and phonons in superlattices. We have recently discovered new Stark Magnetophonon resonances and Superlattice Magnetophonon effects

  • Metal-Insulator transitions and the quantum Hall effect.
    • We have made extensive studies of coupled electron-hole systems including the discovery of a Compensated Quantum Hall Effect, counter propagating edge states and non-local transport.

    When the numbers of electrons and holes are nearly equal a zero Hall resistance state forms as shown here and the edge states of the electrons and holes become mixed. More details of these effects are given in a presentation available here (1.1Mb). 

    We study the quantum Hall effect in a variety of materials systems, including InSb, InAs and GaSb.

    More information on magneto-optical experiments can be found at the Virtual Laboratory

    2. Magneto-Optics



    Our Research programme is looking at electron-electron and electron-hole interactions using:

  • Interacting electron gases which form Quantum Hall and Fractional Quantum Hall systems with.


    • i. Interband emission and absorption and dual resonance techniques such as Far Infrared Modulated PhotoLuminescence (FIRM-PL)

    ii. Pressure to tune the electron g-factor to zero. This is thought to enhance the possibility of forming spin-textured states known as Skyrmions.

  • Electron-hole gases in bilayer systems


    • 1. Cyclotron and subband resonances are studied in semimetallic InAs/GaSb structures which have steady state electron and hole gases, looking for excitonic interactions and possible excitonic insulators and condensates.


    More information on magneto-optical experiments can be found at the Virtual Laboratory.