Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 97: Superconducting Diodes and Ratchets

TT 97.4: Talk

Friday, March 13, 2026, 10:15–10:30, CHE/0089

Field-Free Superconducting Diode and Topological FFLO States in Altermagnetic Shiba Chains — •Dibyendu Samanta and Sudeep Kumar Ghosh — Indian Institute of Technology, Kanpur 208016, India

The superconducting diode effect (SDE), characterized by a directional asymmetry in the critical supercurrents, typically requires external magnetic fields to break time-reversal symmetry-posing challenges for device integration. Here, we demonstrate a field-free realization of the SDE in a helical Shiba chain proximitized by a d-wave altermagnet. Using a self-consistent Bogoliubov-de Gennes approach, we uncover a topological Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state hosting tunable Majorana zero modes at the chain ends. This state, stabilized by the interplay between the exchange coupling of magnetic adatoms and the induced altermagnetic spin splitting, can be tuned by an applied supercurrent. Crucially, the same FFLO phase supports strong nonreciprocal supercurrents, achieving diode efficiencies exceeding 45% without applied magnetic fields. The d-wave altermagnet simultaneously breaks time-reversal and inversion symmetries via momentum-dependent spin splitting, enabling both topological superconductivity and the field-free SDE in a junction-free setting. Our findings establish Shiba chain-altermagnet heterostructures as a scalable platform for supercurrent-tunable topological superconductivity and intrinsic, field-free superconducting diodes for dissipationless quantum technologies.

Keywords: Superconducting diode effect; Altermagnet; Topological FFLO superconductivity; Majorana zero modes; Shiba chain