Nonequilibrium phenomena in two-dimensional electron Corbino rings at large filling factors A.A. Bykov, I.S. Strygin, D.V. Dmitriev Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Science, 630090 Novosibirsk, Russia S. Dietrich, S.A. Vitkalov Physics Department, City College of the City University of New York, New York 10031, USA APPLIED PHYSICS LETTERS 100, 251602 (2012) PHYSICAL REVIEW B 87, 081409(R) (2013) UIWSPS-2014 1

1. Hall-bar and Corbino-disk 2. 2D system at large filling factors 3. Zener tunneling between Landau orbits and Zero-differential resistance in Hall bars 4. Samples and experiment 5. Zener tunneling between Landau orbits in two-dimensional electron Corbino rings 6. Zero-differential conductance of two-dimensional electrons in crossed electric and magnetic fields 7. Summary UIWSPS-2014 2

Hall-bar Corbino-disk rxx = (V23 /I14)(W/L) = (V65 /I14)(W/L) rxy = V26 /I14 = V35 /I14 sxx = (I12/2pV12)ln(rout/rin) sxx = rxx /( rxx2 + rxy2) sxy = rxy /( rxx2 + rxy2) rxx = sxx /( sxx2 + sxy2) rxy = sxy /( sxx2 + sxy2) = 1/ UIWSPS-2014 3

UIWSPS-2014 4

UIWSPS-2014 5

Quantum Hall Effect UIWSPS-2014 6 K. v Klitzing, G. Dorda, M. Pepper. PRL 45, 494 (1980). D. C. Tsui, H. L. Stormer, A. C. Gossard. PRL 48, 1559 (1982). UIWSPS-2014 6

2D systems at large filling factors I. A. Dmitriev, A.D. Mirlin, D. G. Polyakov, M. A. Zudov REV. MOD. PHYS. 84 (2012) B = 0 B > 0 B > 0 = /tq > wc g = g0 << wc > wc e e g(e) = g0[1-2lcos(2pe/wc)] g0 = m*/p2 fT l = exp(-p/wctq) EF fT = 1/{exp[(e - EF )/kBT] +1} E1 g0 g (e) UIWSPS-2014 7

Nonlinear magnetotransport in Hall bar UIWSPS-2014 8

Zener tunneling between Landau orbits UIWSPS-2014 9

Zener tunneling between Landau orbits in Hall bar “HIRO” 2RceEH = lwc DkF = 2kF C. L. Yang, J. Zhang, R. R. Du, J. A. Simmons, J. L. Reno. PRL 89, 076801 (2002). UIWSPS-2014 10

Zero-Differential Resistance State of Two-Dimensional Electron Systems in Strong Magnetic Fields A. A. Bykov, J-Q. Zhang, S, Vitkalov, A. Kalagin, A. Bakarov, PRL 99, 116801 (2007). UIWSPS-2014 11

Heterostructure GaAs/AlAs n ~ 81015 м-2 m ~ 200 м2/Вс T = 1.6 - 4.2 K B < 2 T UIWSPS-2014 12

UIWSPS-2014 13

Magnetic field dependencies of the conductance of "narrow" and "wide" 2D electronCorbino discs UIWSPS-2014 14

Zener tunneling between Landau orbits in Corbino rings UIWSPS-2014 15

Zener tunneling between Landau orbits in Corbino rings UIWSPS-2014 16

Zero-differential conductance of two-dimensional electrons in crossed electric and magnetic fields UIWSPS-2014 17

UIWSPS-2014 18

Summary Current induced oscillations of differential conductivity of two-dimension electrons, placed in quantizing magnetic fields, are observed in GaAs quantum wells in Corbino geometry. The oscillations are periodic in the square of the inverse magnetic field and occur in Corbino rings with a width which is much lesser than the radius of the rings. The conductance oscillations are described by Zener tunneling between Landau orbits in the absence of the Hall electric field. An electronic state with zero-differential conductance is found in nonlinear response to an electric field E applied to two dimensional Corbino discs of highly mobile carriers placed in quantizing magnetic fields. The state occurs above a critical electric fieldE > Eth at low temperatures and is accompanied by an abrupt dip in the differential conductance. UIWSPS-2014 19