IFIMAC+ICMM Joint Seminar Series focuses on cutting-edge research on condensed matter physics, bringing speakers from all over the world to our Cantoblanco Campus. All talks are streamed online. Some of them will be celebrated on campus and onsite participation will also be possible. You need to subscribe to our mailing list at the link provided below to get the links to the seminar room. https://listas-correo.uam.es/sympa/subscribe/seminarios-ifimac-icmm-l


Extremely long range Josephson effect across a half metallic ferromagnet

Jacobo Santamaría, Universidad Complutense de Madrid

November 25, 2021, 12:00 CET

This talk will be celebrated in a hybrid format. On-site venue: Salón de Actos, Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC. Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain)


The Josephson effect results from the coupling of two superconductors across a non-superconducting spacer to yield a quantum coherent state. In ferromagnets, singlet (opposite-spin) Cooper pairs decay over very short distances, and thus Josephson coupling requires a nanometric spacer. This is unless equal-spin triplet pairs are generated which, theoretically, can couple superconductors across much longer distances. Despite many experimental hints of triplet superconductivity at ferromagnet/superconductor interfaces, long range triplet Josephson effects across ferromagnetic barriers have remained elusive. In this talk I will discuss a micron-range Josephson coupling in planar junctions across the half-metallic ferromagnet La0.7Sr0.3MnO3 combined with the high-temperature superconductor YBa2Cu3O7. These display the hallmarks of the Josephson physic, namely critical current oscillations due to flux quantization (Fraunhofer pattern) and phase locking under microwave excitation (Shapiro steps) [1]. The marriage of high-temperature quantum coherent transport and full spin polarization brings unique opportunities for the practical realization of superconducting spintronics, and enables novel strategies for devices in quantum technologies.

[1] Nature Mater (2021), in print

Work done in collaboration with D. Sanchez-Manzano1, S. Mesoraca2, F. Cuellar1, M. Cabero3, V. Rouco1, G. Orfila1, X. Palermo2, A. Balan2, L. Marcano5, A. Sander2, M. Rocci1, J. Garcia-Barriocanal 5, F. Gallego1, J. Tornos1, A. Rivera1, F. Mompean6., M. Garcia-Hernandez 6, J. M. Gonzalez-Calbet3, C. Leon1, S. Valencia5, C. Feuillet-Palma7, N. Bergeal7, A.I. Buzdin8, J. Lesueur7, Javier E. Villegas2, J. Santamaria1,*.

1 GFMC. Dept. Fisica de Materiales. Facultad de Fisica. Universidad Complutense. 28040 Madrid

2 Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau. France

3 Centro Nacional de Microscopia Electronica. Universidad Complutense 28040 Madrid.

4 Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489, Berlin, Germany

5 Characterization Facility, University of Minnesota, 100 Union St, Minneapolis, MN 55455, USA

6 Instituto de Ciencia de Materiales de Madrid ICMM-CSIC 28049 Cantoblanco. Spain

7 Laboratoire de Physique et d’Etude des Matériaux, CNRS, ESPCI Paris, PSL Research University, UPMC, 75005, Paris, France

8 Université Bordeaux, CNRS, LOMA, UMR 5798, F-33405 Talence, France