Superconductor/ferroic hybrids

DIPC Seminars

Javier E. Villegas , Unité Mixte de Physique CNRS/Thales
Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
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Superconductor/ferroic hybrids **Superconductor/ferroic hybrids** Javier E. Villegas Unité Mixte de Physique CNRS/Thales, Palaiseau, France The physical properties of hybrid structures may radically differ from those of the individual constituents’, as novel -sometimes unexpected- behaviors arise due to competing interactions at the interfaces. Interestingly, external stimuli that have moderate effects on each of the constituents separately may induce dramatic effects on the hybrid structure, as they break the delicate balance resulting from the interface interactions. This allows engineering artificial materials with new functionalities [1]. Superconductor/ferroic hybrids provide with many examples of this. One interesting possibility is to couple one of the constituents’ sensitivity to external stimuli (e.g. electric or magnetic fields) to a measurable, strongly varying physical property of the other constituent (e.g. the electrical resistance in a superconductor). I will show that this is possible via the effects on the superconductor of the (magnetic or electric) stray fields from the ferromagnetic [2] or ferroelectric subsystem [3,4]. These effects yield a giant, hysteretic, remnant magneto (or electro) resistance. Furthermore, through this mechanism and owing to the ability to reversibly design the ferroic domain structure, it is possible to produce a nanoscale modulation of the superconducting condensate [3]. This opens new possibilities for superconducting nano-electronic devices, which may exploit flux quantization [5,6] and Josephson coupling effects. Another interesting possibility is to literally merge the most distinctive property of each of the constituents in order to observe truly hybridized behavior. In the second part of the talk, we will show an example on how to unite the long-range phase-coherent charge transport characteristic of superconductivity and the spin-polarized charge transport characteristic of ferromagnetism [7], which may open the door to novel spintronic devices. This is demonstrated in experiments with heterostructures that combine YBa2Cu3O7-x and the half-metallic ferromagnet La0.7Ca0.3MnO3. [8] **References** [1] M. Bibes, J. E. Villegas and A. Barthélémy, Advances in Physics, **60** (2011) 5. [2] C. Visani, P. J. Metaxas, A. Collaudin, B. Calvet, R. Bernard, J. Briatico, C. Deranlot, K. Bouzehouane, and J. E. Villegas, Phys. Rev. B **84** , 054539 (2011). [3] A. Crassous, R. Bernard, S. Fusil, K. Bouzehouane, D. Le Bourdais, S. Enouz-Vedrenne, J. Briatico, M. Bibes, A. Barthélémy, and Javier E. Villegas, Phys. Rev. Lett. **107** (2011) 247002\. [4] A. Crassous, R. Bernard, S. Fusil, K. Bouzehouane, J. Briatico, M. Bibes, A. Barthélémy, and Javier E. Villegas, Jour. Appl. Phys. **113** (2013) 024910. [5] _ _ I. Swiecicki, C. Ulysse, T. Wolf, R. Bernard, N. Bergeal, J. Briatico, G. Faini, J. Lesueur and J. E. Villegas, __ Phys. Rev. B **85** (2012) 224502. [6] J. E. Villegas, _et al. _Nanotechnology 22 (2011) 075302. [7] F. S. Bergeret, A. F. Volkov, and K. B. Efetov, Rev. Mod. Phys. 77, 1321 (2005). [8] C. Visani, Z. Sefrioui, J. Tornos, C. León, J. Briatico, M. Bibes, A. Barthélémy, J. Santamaría and Javier E. Villegas, Nature Physics **8** (2012) 539.