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Transport properties: conductance and thermopower. Rok Žitko Institute Jožef Stefan Ljubljana, Slovenia. Transport in nanostructures. Landauer formalism. Density of states per unit length:. (Includes factor 2 for spin). For T(E)=1 (ballistic conductor):. In general, at T=0:. - PowerPoint PPT Presentation
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Transport properties: conductance and thermopower
Rok ŽitkoInstitute Jožef StefanLjubljana, Slovenia
Transport in nanostructures
Landauer formalism
Density of states per unit length:
(Includes factor 2 for spin)
For T(E)=1 (ballistic conductor):
In general, at T=0:
Multi-channel leads:
resistance
quantized contact resistance
Scattering theory
quasiparticle phase shifts
Spin symmetry, single effective channel:
Keldysh approach
One impurity:
Also known as the Meir-Wingreen formula
Relection symmetric problems:
Conductance of quantum dot (SIAM)
Finite temperatures
Effect of the magnetic field
A B
V~0
A B
V>0
I
V
dI/dV
V
A B
V~0
A B
eV>hw
I
V
dI/dV
Vħw
ħw
ħw
Inelastic scattering
Information about internal degrees of freedom!
Linear response theory for calculating the conductance of nanostructures
Kubo (1957)
Standard approach:
Difficulty: the slope is difficult to calculate reliably!
Solution: we can work with the global operator Nn itself!
Test case: single-impurity Anderson model
Proposed application:conductance of a S-QD-N structure
• Open problem: the transition from G=4e2/h to G=2e2/h conductance as the gap closes
1) 2)
3) 4)
Anyone interested?
Transport integrals, thermopower
B=0 d=0 (particle-hole symmetric point)
(charge) Seebeck coefficient spin Seebeck coefficient
Spin thermopower is a sensitive probe of the response of the system in magnetic field.
Žitko, Mravlje, Ramšak, Rejec,
manuscriptin preparation.