Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor system

Details Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor system Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor system

2001-03-27

arxiv.org/abs/cond-mat/0103550v1

Physics

Condensed Matter

Mesoscale and Nanoscale Physics

18 pages, 8 figures, LateX

Scientific paper

10.1088/0953-8984/13/39/307

We study Andreev bound states and $\pi $-junction transition in a superconductor / quantum-dot / superconductor (S-QD-S) system by Green function method. We derive an equation to describe the Andreev bound states in S-QD-S system, and provide a unified understanding of the $\pi $-junction transition caused by three different mechanisms: (1) {\it Zeeman splitting.} For QD with two spin levels $E_{\uparrow}$ and $E_{\downarrow}$, we find that the surface of the Josephson current $I(\phi =\frac \pi 2)$ vs the configuration of $(E_{\uparrow},E_{\downarrow})$ exhibits interesting profile: a sharp peak around $E_{\uparrow}=E_{\downarrow}=0$; a positive ridge in the region of $E_{\uparrow}\cdot E_{\downarrow}>0$; and a {\em % negative}, flat, shallow plain in the region of $E_{\uparrow}\cdot E_{\downarrow}<0$. (2){\it \ Intra-dot interaction.} We deal with the intra-dot Coulomb interaction by Hartree-Fock approximation, and find that the system behaves as a $\pi $-junction when QD becomes a magnetic dot due to the interaction. The conditions for $\pi $-junction transition are also discussed. (3) {\it \ Non-equilibrium distribution.} We replace the Fermi distribution $f(\omega)$ by a non-equilibrium one $\frac 12[ f(\omega -V_c)+f(\omega +V_c)] $, and allow Zeeman splitting in QD where $% E_{\uparrow}=-E_{\downarrow}=h.$ The curves of $I(\phi =\frac \pi 2)$ vs $% V_c$ show the novel effect of interplay of non-equilibrium distribution with magnetization in QD.

Affiliated with

Also associated with

No associations

Rating

Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor system does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Andreev bound states and $π$-junction transition in a superconductor / quantum-dot / superconductor system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-28065