A. Ramšak 1,2 and T. Rejec 2 1 Faculty of Mathematics and Physics, University of Ljubljana 2 J. Stefan Institute, Ljubljana, Slovenia Conductance of nano-systems with interaction
Nature 417, (13 June 2002) Kondo resonance in a single-molecule transistor WENJIE LIANG*, MATTHEW P. SHORES†, MARC BOCKRATH*, JEFFREY R. LONG† & HONGKUN PARK*
open system
Conductance: ΔI = GΔV +ΔV
Conductance: ΔI = GΔV +ΔV IF the system is the Fermi liquid
odd even Gogolin (1994): persistent currents for non-interacting systems
Conductance formulas: two-point energy: Favand and Milla (1998): for non-interacting systems, g<<1 Molina et al. (2003)
Conductance formulas: two-point energy: persistent current: Sushkov (2001) Meden and Schollwöck (2003)
Conductance formulas: two-point energy: persistent current: charge stiffness:
min max charge stiffness:
note: Fermi liquid linear conductance zero temperature non-interacting single-channel leads
Proof of the method Step 1. Conductance of a Fermi liquid system at T=0 Kubo T=0 define (n.i.: Fisher-Lee) ‘Landauer’
Step 2. Quasiparticle Hamiltonian (Landau Fermi liquid)
Step 3. Quasiparticles in a finite system N
Step 4. Quasiparticle energies ‘single (quasi)particle energy’; also eigenenergy of Φ dependence of is as in non-interacting systems
Step 5. Non-interacting systems
open system
ring system
Step 5. Non-interacting system ground-state energy:
Examples 1 Noninteracting system
2 Anderson impurity model Wiegman, Tsvelick (1982)
3 Double quantum dot Oguri, PRB 56, (1997)
broken time reversal symmetry (e.g., due to external magnetic field) : 4 Aharonov-Bohm system (Kondo-Fano)
broken time reversal symmetry (e.g., due to external magnetic field) : 4 Aharonov-Bohm system (Kondo-Fano)
Bułka, Stefanski, PRL (2001) Hofstetter, König, Schoeller, PRL (2001)
Summary: 1.IF the system is Fermi liquid … 2.Calculate the ground-state energy of the interacting (ring) system 3.Determine the conductance from the two (four)-point energy formula T. Rejec and A. Ramšak, PRB 68, (2003) T. Rejec and A. Ramšak, PRB 68, (2003)
‘0.7 anomaly’
1988
“0.7 structure” Thomas et al. PRL 77, 136 (1996):
Resonant scattering
Singlet transmission Triplet transmission
Results: “1/4” and “3/4” anomalies
PRB 44, (1991) exp.: “0.7” and “0.3” Phil. Mag. 77, 1213 (1998)
V-groove
PRL 2002
Summary “0.7” anomaly is “ 1/4 ”+” 3/4 ” anomaly anomalies also in S and in magnetic field “1/2” extended Anderson model (Kondo) open problems: - Kondo physics? - doping dependence? - “ 0.5 ” anomaly Rejec, Ramšak, Jefferson, PRB 67, (2003) and refs. therein
Tomi Rejec
Narrow wires (10~20 nm) “V”-groove