Excitonic BEC in in Quantum Hall Bilayers
Ramin Abolfath NRCC Anton Burkov UCSB Jim Eisenstein Cal Tech. Steve Girvin Yale Yogesh Joglekar LANLJairo Sinova Texas A&M Ady Stern Weizmann Leo Radzihovsky UCAlvaro Nunez UTAEnrico Rossi UTAGiovanni Vignale UMC University of Texas at Austin
May 2005
Current - Spin-Torque
This feature allows you to specify a direct interactionbetween spin dependent current that is generated
in a ferromagnetic layer (polarizer), which isincident upon a second ferromagnetic layer
(analyzer) through a paramagnet.
**Click on regions of the menu for descriptions of the features.**
Landau Liftshitz Gilbert
Electron-Hole Pairs(n’,n)=(,) =Ferromagnetism(n’,n)=(c,v) = Excitonic BECs
(n’,n)=(TopLayer,BottomLayer) Order Parameter
Counterflow Superfluidity
AlGaAs AlGaAsGaAs
100 A
Quantum Well
e-
energ
y
Ga
As
Si
AlGaAs
GaAs
100 A
AlGaAs
Double Quantum Well
-
Quantum Wells
Ga As
ultra highvacuum
heated cells
high qualityGaAs substrate
Al
Molecular Beam Epitaxy
Pfeiffer - Bell Labs
Shayegan – Princeton
Electrons and Holes in the QH Regime
Add magnetic field
Particle-hole transformation
Assemble Bilayer
Superflow in Electron-Electron Bilayers
Kellogg and Eisenstein cond-mat/0401521
Hall Angle Not Large
σxx 1000 e2/h
300
200
100
0Tu
nn
elin
g C
on
du
cta
nce
(
10-9
-1
)
-5 0 5Interlayer Voltage (mV)Interlayer Voltage
0
Tun
nelin
g ra
te
0
Josephson-like Currents
Josephson Effect
J.J. Dynamics
eV = 0
Δ sin(φ) = Ibias
Correct Explanation?
300
200
100
0Tunn
elin
g C
ondu
ctan
ce
(10
-9
-1)
-5 0 5Interlayer Voltage (mV)0
Collective Dynamics & Dissipation
Ferromagnets vs. Josephson Junctions vs. Bilayers
J.J. Dynamics
Thin Film Ferromagnet
Dynamics
Thin Film Ferromagnets Buhrman & Ralph, MSU, NIST, Orsay
Thin Film Ferromagnet
Dynamics
Spin Transfer
Transport Orbitals
eV
Condensate Orbitals
K = X l2
Coherent Edge Transport
Empl 10-6 eVΔQP 10-3 eV
G e2/h
Δt 10-9 eV
V* 10-6 Volts
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