DQMP Seminar by Professor Alexander Balatsky

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Date(s) - 24/05/2016
13 h 00 min - 14 h 30 min

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Mardi 24 mai 2016 à 13.00
Auditoire Stückelberg
Ecole de physique

Alexander Balatsky – Los Alamos National Laboratory, Nordita USA

Superconductivity and  quantum  paraelectric fluctuations in STO

Following the pioneering discovery of the superconductivity in STO interfaces the field of  collective states at interfaces has been rapidly growing. Recently  we come to realize that the key to a lot of puzzles in these devices lies in the complicated states of bulk STO. STO is one of the earliest examples of superconductivity in oxides. Superconducting state is STO exhibits the dome as a function of doping. STO is also a known quantum paraelectric.  Historically ferroelectric quantum criticality and superconducting dome in STO were assumed to be unrelated. We propose that they are in fact intimately connected.  We suggest that quantum criticality can induce superconductivity due to quantum ferroelectric fluctuations. I will present our results on investigation of  the origin of superconductivity in doped STO using a combination of density functional and strong coupling theory. Our approach suggests a model in which the soft mode fluctuations provide the pairing interaction for superconductivity carriers.  Based on this model I will illustrate our  prediction that the highest critical temperature will increase and shift to lower carrier doping with increasing 18O isotope substitution, a scenario that is experimentally verifiable.  I will also illustrate the ongoing debate on the multiband nature of the superconducting state in bulk STO and in related heterostructure devices.

 

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J. Edge et al Phys. Rev. Lett.115, 247002 (2015)

Réalisation : Sur Mesure concept