Extremely long-range Josephson coupling across a half-metal 

See our recent publication in Nature Materials !

The Josephson effect results from the coupling of two superconductors across a spacer such as an insulator, a normal metal or a ferromagnet to yield a phase-coherent quantum state. However, in junctions with ferromagnetic spacers, very long-range Josephson effects have remained elusive.

Here we demonstrate extremely long-range (micrometric) high-temperature (tens of kelvins) Josephson coupling across the half-metallic manganite La0.7Sr0.3MnO3 combined with the superconducting cuprate YBa2Cu3O7.

YBCO/LCMO interface images and micrograph of the planar Josophson junctions

These planar junctions, in addition to large critical currents, display the hallmarks of Josephson physics, such as critical current oscillations driven by magnetic flux quantization and quantum phase-locking effects under microwave excitation (Shapiro steps). The latter display an anomalous doubling of the Josephson frequency predicted by several theories. In addition to its fundamental interest, the marriage between high-temperature, dissipationless quantum coherent transport and full spin polarization brings opportunities for the practical realization of superconducting spintronics, and opens new perspectives for quantum computing.

Field modulation of the Josphson current depending on the relative direction between the current and the magnetic field

This work is a collaboration between the University Complutense of Madrid, ESPCI Paris, LOMA Bordeaux, and my group at UMPhy CNRS/Thales. The work here has been financed by grants ERC “SUSPINTRONICS” and ANR “SUPERTRONICS”

“Extremely long-range, high-temperature Josephson coupling across a half-metallic ferromagnet” D. Sanchez-Manzano, S. Mesoraca, F. A. Cuellar, M. Cabero, V. Rouco, G. Orfila, X. Palermo, A. Balan, L. Marcano, A. Sander, M. Rocci, J. Garcia-Barriocanal, F. Gallego, J. Tornos, A. Rivera, F. Mompean, M. Garcia-Hernandez, J. M. Gonzalez-Calbet, C. Leon, S. Valencia, C. Feuillet-Palma, N. Bergeal, A. I. Buzdin, J. Lesueur, Javier E. Villegas & J. Santamaria Nature Materials (2021). Free access here

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s