Dimitri Roditchev, Institut des Nanosciences de Paris, Université Pierre et Marie Curie-Paris

Mardi 31 Mai 2011, 16h00
Amphi Boreau, Esc C, 2ème etage

Confinement-Induced Vortex Fusion and Giant Vortex States in Superconductors

Dimitri Roditchev

When put in rotation, macroscopic quantum condensates develop a very peculiar collective response : They split in a huge number of small quantum tornados - vortices - that organize in a lattice [1]. The vortex currents circulate owing to the gradient of the condensate wave function Ψ(r) that accumulates exactly 2π phase difference around each vortex core where Ψ(r) vanishes. This general quantum phenomenon was observed in superconductors [2], superfluids [3], Bose-Einstein condensates of ultra-cold atoms [4]. The confinement of quantum condensates to scales comparable to their characteristic coherence length should modify the vortex lattice, leading to novel vortex arrangements [5-9]. Moreover, new quantum objects - Giant Vortices, characterized by the phase accumulation L x 2π, L ≥ 2 (L being the orbital quantum number or winding factor) were predicted to exist owing to the spatial confinement of the superconducting condensate [8]. This prediction remained till now experimentally unconfirmed.
In my talk I will discuss the results of the recent direct Scanning Tunneling Spectroscopy (STS) experiment by our group in which we addressed the problem of the quantum vortex configurations in strongly confined superconductors. The strong confinement regime was achieved in in-situ grown ultra-thin single nanocrystals of Pb which lateral size was tuned to few coherence lengths. Upon an external magnetic field, the STS at 0.3K revealed novel ultra-dense arrangements of single Abrikosov vortices characterized by inter-vortex distance up to three times shorter than the bulk critical one. At yet stronger confinement we discovered the Giant Vortex phase ; the spatial evolution of the excitation tunneling spectra in the cores of these unusual quantum objects was explored. I will show that the magnetic energy is not relevant in the observed phenomena and thus, the observed Giant Vortex phase should be a common feature of all confined quantum condensates such as superfluids, Bose-Einstein condensates of cold atoms etc.

[1] A. A. Abrikosov, Soviet Physics JETP 5, 1174 (1957) ; Nobel Lecture (2003).
[2] U. Essmann, H. Trauble, Physics Letters 24A, 526 (1967).
[3] E. J. Yarmchuk, M. J. V. Gordon, R. E. Packard, Phys. Rev. Lett. 43, 214217 (1979).
[4] J. R. Abo-Shaeer, C. Raman, J. M. Vogels, W. Ketterle, 292, 476 (2001).
[5] D. Saint-James, Phys. Lett. 15, 1 13 (1965).
[6] H. J. Fink, A. G. Presson, Phys. Rev. 151, 219 (1966).
[7] P. S. Deo, V. A. Schweigert, F. M. Peeters, A. K. Geim, Phys. Rev. Lett. 79, 4653 (1997).
[8] V. A. Schweigert, F. M. Peeters, P. Singha Deo, Phys. Rev. Lett. 81, 2783 (1998).
[9] L. F. Chibotaru, A. Ceulemans, V. Bruyndoncx, V. V. Moshchalkov, Nature 408, 833 (2000).


Haut de page



À lire aussi...

Olivier Crauste, Strained HgTe Topological Insulator : Transport measurements & ARPES results

Jeudi 20 Juin 2013, 14hAmphi Holweck, Esc C, 1ème etage Strained HgTe Topological Insulator : Transport measurements & ARPES results Olivier (…) 

> Lire la suite...

Aharon Kapitulnik

Jeudi 11 Mai 2017 à 14h00 Amphi Holweck, Esc C 1ème etage TRANSPORT IN STRONGLY CORRELATED BAD METALS Abstract : The standard paradigm for (…) 

> Lire la suite...