Transcript Заголовок слайда отсутствует

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)
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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
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Hall-bar
2
W
Corbino-disk
3
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2rout
4
L
1
sxx = (I12/2pV12)ln(rout/rin)
rxy = V26 /I14 = V35 /I14
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2rin
2
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rxx = (V23 /I14)(W/L) = (V65 /I14)(W/L)
sxx = rxx /( rxx2 + rxy2)
sxy = rxy /( rxx2 + rxy2)
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σˆ
= 1/
ρˆ
rxx = sxx /( sxx2 + sxy2)
rxy = sxy /( sxx2 + sxy2)
3
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Quantum Hall Effect
K. v Klitzing, G. Dorda, M. Pepper.
PRL 45, 494 (1980).
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D. C. Tsui, H. L. Stormer, A. C. Gossard.
PRL 48, 1559 (1982).
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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
<< wc
B=0
g = g0
e
e
B>0
 > wc
= /tq > wc
g(e) = g0[1-2lcos(2pe/wc)]
g0 = m*/p2
l = exp(-p/wctq)
fT
EF
fT = 1/{exp[(e - EF )/kBT] +1}
E1
g0
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0
g (e)
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Nonlinear magnetotransport in Hall bar
~ Iac
Rxx = Vdc/Idc
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Idc
Vdc, Vac
rxx = Vac/Iac
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Zener tunneling between Landau orbits
N+2
Энергия электрона
F = - eEH
N+1
kF
w
C
EF
N
Rc
N+1
Rc
N
kF
R = 2Rc
Координата центра электронной орбиты
R = 2Rc
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2RceEH = l wc
k = 2kF
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Zener tunneling between Landau orbits in Hall bar
“HIRO”
2RceEH = lwc
kF = 2kF
C. L. Yang, J. Zhang, R. R. Du, J. A. Simmons, J. L. Reno. PRL 89, 076801 (2002).
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Zero-Differential Resistance State of Two-Dimensional Electron Systems in
Strong Magnetic Fields
150
100
100
rxx ()
B = 0.8 T
T = 2.1 K
0
-20
Idc (A)
0
r xx ()
50
20
0
Idc = 4 A
Idc = 8.4 A
-50
0.0
Idc = 20 A
0.2
0.4
B (T)
0.6
0.8
1.0
A. A. Bykov, J-Q. Zhang, S, Vitkalov, A. Kalagin, A. Bakarov, PRL 99, 116801 (2007).
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Heterostructure GaAs/AlAs
n ~ 81015 м-2
 ~ 200 м2/Вс
T = 1.6 - 4.2 K
B<2T
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Magnetic field dependencies of the conductance
of "narrow" and "wide" 2D electronCorbino discs
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Zener tunneling between Landau orbits in Corbino rings
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Zener tunneling between Landau orbits in Corbino rings
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Zero-differential conductance of two-dimensional
electrons in crossed electric and magnetic fields
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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.
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