| EPSRC Reference: |
GR/R37548/01 |
| Title: |
Milli Kelvin Magnetometry Studies of the Quantum Hall Effects |
| Principal Investigator: |
Usher, Dr A |
| Other Investigators: |
|
| Researcher Co-Investigators: |
|
| Project Partners: |
|
| Department: |
Physics |
| Organisation: |
University of Exeter |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
01 September 2001 |
Ends: |
31 August 2004 |
Value (£): |
196,494
|
| EPSRC Research Topic Classifications: |
| Magnetism/Magnetic Phenomena |
|
|
| EPSRC Industrial Sector Classifications: |
| No relevance to Underpinning Sectors |
|
|
| Related Grants: |
|
| Panel History: |
|
|
Summary on Grant Application Form |
|
The fractional and integer quantum Hall effects are two of the most important phenomena to emerge from studies of low-dimensional systems. This proposal uses the novel technique of torque magnetometry to address several major outstanding issues associated with these effects.Magnetisation measurements yield true equilibrium thermodynamic information which allows very direct and explicit tests of theory, but is extremely difficult to obtain using other techniques. Such information is particularly important when studying changes of phase such as those associated with the quantum Hall effects and with formation of the magnetically-induced Wigner solid. We will make a direct thermodynamic measurement of the energy gaps associated with the fractional quantum Hall effect, and measure the order of the Wigner solid transition - both results will be of the highest international significance.We will also study the effects of currents induced by a sweeping magnetic field in the quantum Hall regimes. This is a contact-free transport measurement. Such currents persist after the magnet stops sweeping; we propose to measure their decay time (which is at least several hours), an indicator of how close to zero the resistivity becomes in this extraordinary regime. We have already demonstrated the utility of our contact-free technique in understanding the mechanisms for breakdown of the quantum Hall effects at high currents, and it appears that they might offer a quasilocal probe of the fractional quantum Hall energy gap: we will investigate this is a range of high-quality samples.
|
|
Key Findings |
|
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
|
|
Potential use in non-academic contexts |
|
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
|
|
Impacts |
|
| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
| Summary |
|
| Date Materialised |
|
|
|
|
Sectors submitted by the Researcher |
|
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
|
| Project URL: |
|
| Further Information: |
|
| Organisation Website: |
http://www.ex.ac.uk |