Unconventional supercurrent phase in Ising superconductor Josephson junction with atomically thin magnetic insulator.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34504077.
- Also identified by DOI 10.1038/s41467-021-25608-1 and PMC identifier 8429564.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
In two-dimensional (2D) NbSe<sub>2</sub> crystal, which lacks inversion symmetry, strong spin-orbit coupling aligns the spins of Cooper pairs to the orbital valleys, forming Ising Cooper pairs (ICPs). The unusual spin texture of ICPs can be further modulated by introducing magnetic exchange. Here, we report unconventional supercurrent phase in van der Waals heterostructure Josephson junctions (JJs) that couples NbSe<sub>2</sub> ICPs across an atomically thin magnetic insulator (MI) Cr<sub>2</sub>Ge<sub>2</sub>Te<sub>6</sub>. By constructing a superconducting quantum interference device (SQUID), we measure the phase of the transferred Cooper pairs in the MI JJ. We demonstrate a doubly degenerate nontrivial JJ phase (ϕ), formed by momentum-conserving tunneling of ICPs across magnetic domains in the barrier. The doubly degenerate ground states in MI JJs provide a two-level quantum system that can be utilized as a new dissipationless component for superconducting quantum devices. Our work boosts the study of various superconducting states with spin-orbit coupling, opening up an avenue to designing new superconducting phase-controlled quantum electronic devices.