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Conférence de John T. Wei


John T. Wei, professeur en physique de la matière condensée à l'Université de Toronto, présentera une conférence le jeudi 16 novembre 2017 à 10 h 30, à la salle Tudor-Johnston du Centre Énergie Matériaux Télécommunications de l'INRS à Varennes. 

Le professeur John T. Wei est l'invité du professeur Alain Pignolet. La conférence du professeur Wei s'intitule « Superoxygenation and Straintronic Effects in Cuprate Thin Films ».



Superconducting cuprates in thin-film form have long held the promise for novel device applications, not just for their high critical temperatures (Tc) but also for their epitaxial integrability with other transition-metal oxides and even with silicon [1]. In this talk I will present some recent advances in the synthesis and heterostructuring of the best-known but also most-enigmatic cuprate YBa2Cu3O7. For synthesis, we found that extreme thermodynamics in the form of high-pressure oxygen, up to 700atm at 900C, can induce structural transformation to exotic high-oxidation phases in thin-film samples [2]. For heterostructuring, we found that anisotropic strain due to epitaxial lattice-symmetry mismatch can attenuate the high-Tc superconductivity [3]. For strained heterostructures, our theoretical study also shows that an asymmetric strain can topologically produce a pseudo-magnetic field [4], exemplifying a new concept for "straintronic" devices based on the generation of magnetism using heteroepitaxial strain.
*Work supported by NSERC, CFI/OIT and the Canadian Institute for Advanced Research
[1] K. Ahmadi-Majla et al, preprint arXiv:1710.08600 (2017).
[2] H. Zhang et al, Nanomaterials for Security, p. 45-56, Springer Netherlands (2016).
[3] H. Zhang et al, Applied Physics Letters 103, 052606 (2013).
[4] G. Massarelli et al, preprint arXiv:1707.07683 (2017).
Bienvenue à tous!



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