Chernogolovka, October 2009 Chernogolovka, October 2009 Nolinear nonequilibrium phenomena in stacked Nolinear nonequilibrium phenomena in stacked junctions junctions Vladimir Krasnov Vladimir Krasnov Experimental Condensed Matter Physics Experimental Condensed Matter Physics Fysikum, AlbaNova, Stockholm Fysikum, AlbaNova, Stockholm University University Phonon lasing in stacked Phonon lasing in stacked intrinsic Josephson junctions intrinsic Josephson junctions Motivation: Motivation: • Non-equilibrium phenomena are central in many Non-equilibrium phenomena are central in many superconducting detectors, but may be detrimental for superconducting detectors, but may be detrimental for in superconducting electronics. in superconducting electronics. • “ “ Heat” (Energy) conduction at low Heat” (Energy) conduction at low T T in the absence of in the absence of thermal conductivity thermal conductivity • Extreme non-equilibrium states in stacked JJ – new Extreme non-equilibrium states in stacked JJ – new nonlinear nonlinear phenomena. Superconducting Cascade Laser in phenomena. Superconducting Cascade Laser in THz frequency range THz frequency range
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Chernogolovka, October 2009 Nolinear nonequilibrium phenomena in stacked junctions Vladimir Krasnov Experimental Condensed Matter Physics Fysikum, AlbaNova,
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Chernogolovka, October 2009Chernogolovka, October 2009
Nolinear nonequilibrium phenomena in stacked Nolinear nonequilibrium phenomena in stacked
junctionsjunctions Vladimir KrasnovVladimir Krasnov
Experimental Condensed Matter PhysicsExperimental Condensed Matter Physics Fysikum, AlbaNova, Stockholm UniversityFysikum, AlbaNova, Stockholm University
Phonon lasing in stacked Phonon lasing in stacked intrinsic Josephson junctionsintrinsic Josephson junctions
Motivation:Motivation:
• Non-equilibrium phenomena are central in many superconducting Non-equilibrium phenomena are central in many superconducting detectors, but may be detrimental for in superconducting electronics. detectors, but may be detrimental for in superconducting electronics.
• ““Heat” (Energy) conduction at low Heat” (Energy) conduction at low TT in the absence of thermal in the absence of thermal conductivityconductivity
• Extreme non-equilibrium states in stacked JJ – new Extreme non-equilibrium states in stacked JJ – new nonlinear nonlinear phenomena. Superconducting Cascade Laser in THz frequency rangephenomena. Superconducting Cascade Laser in THz frequency range
E
E
B eV-2
N(E)
eVR 2
2
Bremsstrphonon
Recomb.
Relaxation of non-equilibrium Quasi-ParticlesRelaxation of non-equilibrium Quasi-Particlesin Josephson junctionsin Josephson junctions
Note, that I-V curves are very similar for both solutions. Therefore, power dissipation P=IV is also the same.However, suppression of is much smaller in the radiative state.This is due to radiative cooling = ballistic boson emission from the stack.
Radiative cooling is the only heat transport mechanism considered here, =0.The stack effectively (100% efficiency) converts electric power into boson emission without ac-Josephson effect.
Overdoped Bi-2212-400 -200 0 200 400
0
2
4
6
S811b69.7K75.0K80.0K84.1K87.5K89.9K92.0K
- (
100K
) (m
S)
V (mV)V.M.Krasnov, Phys.Rev.Lett. 97,257003 (2006)
Observation of even-gap peculiarities in Observation of even-gap peculiarities in Bi-2212 intrinsic tunneling characteristics Bi-2212 intrinsic tunneling characteristics
0 20 40 60 800
10
20
30
40
811b 6S/e
4S/e
2S/e
Vol
tage
per
junc
tion
(m
V)
T (K)
Height of the mesa
4a 4bI+
I-
V-
V+
0
0.1
0.2
0.3
0.4
0 500 1000 1500 2000 2500
IV4b124b6a T=4.19K Three-probe
I (m
A)
V(mV)
0
0.1
0.2
0.3
0.4
0 250 500
IV4a124b6aT4_19bFour-probe
V(mV)
I (m
A)
Tripple-mesa with common junctions for injection-detection experiments:
Three and Four-probe measurements
N=52
N=28
N=52
N=28
V.M.Krasnov, Phys.Rev.Lett. 97,257003 (2006)
AA EEBB CCD
BiBi22SrSr22CaCuCaCu22OO8+8+II
VV
V.M.Krasnov, Phys.Rev.Lett. 97,257003 (2006)
Detection of recombination radiationDetection of recombination radiation
0 1 2
1E-3
0.01
0.1
0 1 2
0.01
0.1
1
10
IQP
T =0.5Tc ,
U=0.1,
I=0.1.
eV-2
a)
eV/0=3.0
F
f
f,
F
E'/0
Nonlinearabsorptive solution
Absorption b)
G
g
g, G
/0
Appearance of a second ”radiative solution” at large bias
No net accumulation of QPs at E’=0 – fast QP relaxation due to stimulated emission of low bosons.
Eistence of two solutions is a result of nonlinerity
From O.Heikkilä et al., J.Appl.Phys. 105, 093119 (2009)
Absorptive and Radiative states in stacked IJJs bare some similarity with light emitting and lasing states in heterostructure injection diodes.
Population inversion by electron injection in a superlattice. Note that in LED Jth=10-100 A/cm2 at 300K, Jth~exp(T). For IJJs J = 104 A/cm2 at 4K.
Mesa itself acts as a Fabry-Perot resonator, selecting cavity (Fiske) modes.
Conclusions:Conclusions:
• Linear approximation fails already at relatively small disequilibrium: the Linear approximation fails already at relatively small disequilibrium: the nonequilibrium part has to be small compared to thermal population. nonequilibrium part has to be small compared to thermal population.
• Nonequilibrium effects are always nonlinear at low enough effects Nonequilibrium effects are always nonlinear at low enough effects TT. This . This has to be taken into account in analysis of superconducting devices at low has to be taken into account in analysis of superconducting devices at low TT..
• In stacked IJJIn stacked IJJ extreme nonequilibrium state can be achieved. The obtained extreme nonequilibrium state can be achieved. The obtained radiative state indicates a possibility of realization of a new type of radiative state indicates a possibility of realization of a new type of Superconducting Cascade LaserSuperconducting Cascade Laser (SCL). Unlike existing Josephson (SCL). Unlike existing Josephson oscillators which utilize the ac-Josephson effect for conversion of electric oscillators which utilize the ac-Josephson effect for conversion of electric power into radiation, the SCL is based on direct conversion of electric power power into radiation, the SCL is based on direct conversion of electric power into boson emission via nonequilibrium QP relaxation upon sequential into boson emission via nonequilibrium QP relaxation upon sequential tunneling in stacked junctions. The mechanism is similar to lasing in tunneling in stacked junctions. The mechanism is similar to lasing in semiconducting heterostructures and allows very high radiation efficiency. semiconducting heterostructures and allows very high radiation efficiency.
• Emitted are bosons that participate in pairing. Therefore, nonequilibrium Emitted are bosons that participate in pairing. Therefore, nonequilibrium intrinsic tunneling spectroscopy may provide a direct probe for HTSC coupling intrinsic tunneling spectroscopy may provide a direct probe for HTSC coupling mechanism. mechanism.