Macroscopic persistent current in the quantum Hall regime

Abstract

We have observed stable de voltages between two edges of a loop structure in the quantum Hall condition without any external current, which is believed to be the Hall voltages due to a persistent circulating current around the rectangular two-dimension al-electron-gas loop, 4.0 mm by 6.0 mm in size and 0.10 mm in width. The persistent current, as much as 6 mu A at 15 mK estimated from the quantum Hall relation, indicates that two unequal edge currents with opposing directions along both edges do exist in the equilibrium quantum Hall condition. The reversible temperature dependence revealed that the persistent current stays constant from 15 mK to 0.3 K, but slowly decreases to half-value at 0.5 K and becomes nearly zero (but not absolutely zero) at 1.0 K.