Self-organised criticality in the quantum Hall effect

We have measured breakdown of the quantum Hall effect in various two-dimensional electron gases formed in MBE-grown GaAs-(Al,Ga)As modulation-doped heterostructures around filling factor ν=2, using a contact-free method. In this method, circulating eddy currents are induced in the sample upon sweeping the magnetic field, and are detected via their magnetic moment using a sensitive magnetometer. At sufficiently high sweep rates, and temperatures below about View the MathML source, the induced eddy current peak size saturates, and often a ‘noisy’ breakdown of the current is observed superimposed on the main eddy current peak. We describe a simple interpretation of this breakdown in terms of a self-organised criticality model of breakdown of the quantum Hall effect, due to the strong Hall field perpendicular to the eddy current direction.