Title: Thermal transport in mesoscopic hybrid nanostructures: application to refrigeration
1Thermal transport in mesoscopic hybrid
nanostructures application to refrigeration
Francesco Giazotto NEST CNR-INFM and Scuola
Normale Superiore Pisa, ITALY
Physique Quantique Mésoscopique
Aussois, France, 19-22 March 2007
2Collaboration
F. Taddei, C. Castellana S. Tirelli C. Pascual
Garcia R. Fazio F. Beltram NEST CNR-INFM and
Scuola Normale Superiore, Pisa, Italy M.
Governale Institut für Theoretische Physik III,
Bochum, Germany F. W. J. Hekking CNRS
Université Joseph Fourier, Grenoble, France J.
P. Pekola O.-P. Saira T. T. Heikkilä N. Kopnin M.
Meschke A. M. Savin Helsinki University of
Technology, HUT, Helsinki, Finland
3Outline
- Part I Heat transport superconducting tunnel
nanostructures - NIS tunnel junctions
- Electron cooling
- Lattice cooling
- SIS and SmS junctions
- Part II Heat transport with ferromagnets and
magnetic barriers - FS junctions operation principle performance
- 2DEG-S systems with localized magnetic fields
- Part III Heat transport in 2DEG-N systems in
quantizing magnetic fields - Operation principle performance
- Electron refrigeration in 2DEG systems
4Electronic microrefrigeration motivations
- On-chip cooling (e.g., detectors, transistors)
- Realization of solid state refrigerators
- (from room temperature to millikelvin range)
- Possibility to reach very low (electron)
temperatures by direct electronic refrigeration
(eventually in the micro-K range) - Control of electron distribution leads to new
effects and devices (e.g., superconducting
transistor, spin sources, magnetization control)
5SIN electron coolers operation principle
6SIN electron coolers electric behavior
7Injection vs relaxation
8Energy relaxation in metals
9SINIS electron coolers performance
10SINIS metallic electron coolers fabrication
- Angle SME
- Al Thermal oxidation
- Al and/or Ti (S leads)
- Cu, Ag, AlMn (N region)
11SINIS refrigerators
12Electron cooling with SIS SmS refrigerators
13Lattice cooling with NIS refrigerators
14Electron cooling in FS junction
FG et al., APL 80, 3784 (2002)
15FS cooler performance I
16Electric transport in SN contacts
17Generation of localized magnetic fields
18Electric transport through localized fields
experiments
19Superconductor-2DEG junction with a localized
magnetic field
20Differential conductance
- Different regimes
- transparent junction
- tunnel-like junction
21Differential conductance
22Requirements and applications
23Heat transport in the presence of localized
magnetic fields
24Performance
25Electronic refrigeration model
26Electronic refrigeration performance
27Landau cooling in 2DEG-N nanostructures
F.G. et al., cond-mat/0703119 (2007)
28Landau cooling I
29Landau cooling II
30Landau cooling electron refrigeration
31Summary
32Landau cooling III
33SINIS-controlled Josephson weak links
34Presence of inelastic scattering
35SINIS quasiparticle distribution function
No inelastic scattering
BCS DOS
36Transport regimes
Strong e-ph interaction (Tgt10K) local potential.
Strong e-e interaction effective T(x)
(hot-electron regime)
Only elastic scattering double-step distribution
(mesoscopic regime)
37Normal metal control line quasiparticle
distribution
VC
Nr
V Vc/2
L
Nl
V -Vc/2
eVc
38SER performance
J. Pekola, FG, and O.P. Saira, Phys. Rev Lett.
98, 037201 (2007)
39Membranes cooling
40Proximity effect and supercurrent
41Heat transistor
O.P. Saira et al., cond-mat/0702361
42FS cooler performance II
COP ?out / ?in
COP 23
Al/CrO2 (half-metallic ferromagnet)
43Radio-frequency single-electron refrigerator (SER)
J. Pekola, FG, and O.P. Saira, Phys. Rev Lett.
98, 037201 (2007)