Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 97: Superconducting Diodes and Ratchets

TT 97.3: Vortrag

Freitag, 13. März 2026, 10:00–10:15, CHE/0089

Josephson diode effect in superconducting hybrids with altermagnets — •Janus F. Niebuhr, Danilo Nikolić, and Matthias Eschrig — Institut für Physik, Universität Greifswald, Felix-Hausdorff-Straße 6, 17489 Greifswald

We present a systematic theoretical study of a ballistic Josephson junction consisting of a d-wave altermagnet (AM) placed between two conventional superconducting leads (S). The study is done by making use of the quasiclassical Green’s function method considering two regimes of (i) a weakly and (ii) a strongly spin polarized altermagnet. The former regime in the limit of highly transmissive S/AM interfaces allows for an analytic treatment. The resulting Josephson current-phase relation (CPR) exhibits 0−π transitions. These significantly depend on the altermagnet’s crystal orientation relative to the junction’s axis by the display of a dominant second harmonic close to the transition. In the regime of strong spin polarization, the altermagnet is coupled to the superconductors via two spin-dependent interfaces, necessary for the creation of equal-spin triplets, which now entirely mediate the current. For a non-coplanar magnetization profile, a quantum-geometric phase emerges. This phase is coupled to spin and enters the Josephson CPR similarly to the phase difference. Consequently, depending on the altermagnetic crystal orientation, the CPR displays an anomalous Josephson effect, as well as a Josephson diode effect. Finally, we perform a harmonic analysis of the CPR discussing the effects in terms of the number of coherently transferred Cooper pairs across the altermagnet.

Keywords: Superconducting Spintronics; Josephson Diode Effect; Altermagnetism