Electrostatic manipulation of High-Tc superconductivity: the hammer and the scalpel

Seminar
QUEST Center event
No
Speaker
Javier E Villegas, CNRS
Date
31/05/2021 - 15:00 - 13:30Add to Calendar 2021-05-31 13:30:00 2021-05-31 15:00:00 Electrostatic manipulation of High-Tc superconductivity: the hammer and the scalpel Electrostatic manipulation of High-Tc superconductivity: the hammer and the scalpel Javier E. Villegas* Unité Mixte de Physique, CNRS, Thales, Université Paris Saclay, Palaiseau, France Field-effect devices based on oxide superconductors constitute an interesting playground to investigate a rich variety of physical phenomena. They also bear much potential for novel functionalities. To illustrate that, I will show transport experiments on junctions between oxide-superconductors and non-superconducting materials, in which the conductance is modulated by electric field effects via different mechanisms. First I will briefly discuss the observation of quasiparticle tunnel electroresistance in superconducting junctions. The term “tunnel electroresistance” was formerly coined to describe a non-volatile resistive switching observed in ferroelectric tunnel junctions upon application of a voltage pulse. This effect, which has opened the door to a new class of memories, can be explained by subtle mechanisms related to the nonvolatile reversal of the ferroelectric polarization. Our experiments with superconducting electrodes demonstrate that the same electroresistance can be produced by a more prosaic mechanism: oxygen electro-migration and the resulting modification of the electrodes’ ground-state. Furthermore, we demonstrate that the electroresistance is orders-of-magnitude stronger for quasiparticles than for normal electrons1,2 Second, I will discuss the electrostatic manipulation of the proximity effect in cuprate superconductor/graphene junctions 3Here, the underlying mechanism is the controlled variation the graphene’s Fermi vector through electrical gating. This allows tuning electron interferences that modulate the Andreev reflection at the superconductor/graphene interface. Furthermore, a different type of interferences –this time controlled by the bias voltage– are observed which are due to geometrical resonances and the coherent propagation of electron/hole pairs in graphene.4 1.        Bégon-Lours et al. Phys. Rev. Mater. 2, 084405 (2018). 2.        Rouco et al. Nat. Commun. 11, 1 (2020). 3.        Perconte et al. Nat. Phys. 14, 25 (2018). 4.        Perconte et al. Phys. Rev. Lett. 125, 087002 (2020).   *In collaboration with: D. Perconte, V. Rouco, C. Ulysse, D. Bercioux, J. Trastoy, A. Sander, P. R. Kidambi, S. Hofmann, B. Dlubak, P. Seneor, F. S. Bergeret, R. El Hage, J. Grandal, J. Briatico, S. Collin, K. Bouzehouane, A.I. Buzdin, G. Singh, N. Bergeal, C. Feuillet-Palma, J. Lesueur, M. Varela, and J. Santamaría   Work supported by the ERC grant Nº 647100, French ANR grant ANR-15-CE24-0008-01 and COST “Nanoscale Coherent Hybrid Devices For Superconducting Quantum Technologies” - Action CA16218. Talk will be via ZOOM: https://us02web.zoom.us/j/8866328706  https://us02web.zoom.us/j/8866328706 המחלקה לפיזיקה physics.dept@mail.biu.ac.il Asia/Jerusalem public
Place
https://us02web.zoom.us/j/8866328706
Abstract

Electrostatic manipulation of High-Tc superconductivity: the hammer and the scalpel

Javier E. Villegas*

Unité Mixte de Physique, CNRS, Thales, Université Paris Saclay, Palaiseau, France

Field-effect devices based on oxide superconductors constitute an interesting playground to investigate a rich variety of physical phenomena. They also bear much potential for novel functionalities. To illustrate that, I will show transport experiments on junctions between oxide-superconductors and non-superconducting materials, in which the conductance is modulated by electric field effects via different mechanisms.

First I will briefly discuss the observation of quasiparticle tunnel electroresistance in superconducting junctions. The term “tunnel electroresistance” was formerly coined to describe a non-volatile resistive switching observed in ferroelectric tunnel junctions upon application of a voltage pulse. This effect, which has opened the door to a new class of memories, can be explained by subtle mechanisms related to the nonvolatile reversal of the ferroelectric polarization. Our experiments with superconducting electrodes demonstrate that the same electroresistance can be produced by a more prosaic mechanism: oxygen electro-migration and the resulting modification of the electrodes’ ground-state. Furthermore, we demonstrate that the electroresistance is orders-of-magnitude stronger for quasiparticles than for normal electrons1,2

Second, I will discuss the electrostatic manipulation of the proximity effect in cuprate superconductor/graphene junctions 3Here, the underlying mechanism is the controlled variation the graphene’s Fermi vector through electrical gating. This allows tuning electron interferences that modulate the Andreev reflection at the superconductor/graphene interface. Furthermore, a different type of interferences –this time controlled by the bias voltage– are observed which are due to geometrical resonances and the coherent propagation of electron/hole pairs in graphene.4

1.        Bégon-Lours et al. Phys. Rev. Mater. 2, 084405 (2018).

2.        Rouco et al. Nat. Commun. 11, 1 (2020).

3.        Perconte et al. Nat. Phys. 14, 25 (2018).

4.        Perconte et al. Phys. Rev. Lett. 125, 087002 (2020).

 

*In collaboration with: D. Perconte, V. Rouco, C. Ulysse, D. Bercioux, J. Trastoy, A. Sander, P. R. Kidambi, S. Hofmann, B. Dlubak, P. Seneor, F. S. Bergeret, R. El Hage, J. Grandal, J. Briatico, S. Collin, K. Bouzehouane, A.I. Buzdin, G. Singh, N. Bergeal, C. Feuillet-Palma, J. Lesueur, M. Varela, and J. Santamaría

 

Work supported by the ERC grant Nº 647100, French ANR grant ANR-15-CE24-0008-01 and COST “Nanoscale Coherent Hybrid Devices For Superconducting Quantum Technologies” - Action CA16218.

Talk will be via ZOOM: https://us02web.zoom.us/j/8866328706 

תאריך עדכון אחרון : 18/05/2021