QHE measurements at high fields and low temperatures

Project Description

Present QHE samples based on GaAs/AlGaAs heterostructures have unprecedented metrological quality, i.e. negligible values of rhoxxmin and wide even plateaus fpr H <= 10 R and T >= 1.5 K are usually found. However little attention has been devoted to investigate odd plateaus aud fractional QHE on these samples for which higher fields (H=15 T) and lower temperatures (T <= 300 mK) are needed.

The objective of this project is two fold: i) To perform QHE measurements on available samples from EUROMET laboratories, in a wider range of temperatures and magnetic field (precision >1 %) than those available in metrological laboratories. ii) To compare the results with theoretical calculations, and to conclude about the possibilities of quality sample improvements for metrology.

Further Information

ICMA will collect samples from LEP, OFM and DFM that will be fully characterized in the range T >= 1.5 K and H <= 10 T. High quality samples will be selected to propose the above experiments at the high magnetic field service SNCI (Grenoble). ICMA belongs to the CSIC and the University of Zaragoza in Spain and represents CEM on EUROMET QHE expert meetings. Funding is provided by the Spanish MIDAS Program (CICYT, REE, UNESA).