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Asaba T, Naritsuka M, Asaeda H, Kosuge Y, Ikemori S, Suetsugu S, Kasahara Y, Kohsaka Y, Terashima T, Daido A, Yanase Y, Matsuda Y. Evidence for a finite-momentum Cooper pair in tricolor d-wave superconducting superlattices. Nat Commun 2024; 15:3861. [PMID: 38719822 PMCID: PMC11078924 DOI: 10.1038/s41467-024-47875-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 04/09/2024] [Indexed: 05/12/2024] Open
Abstract
Fermionic superfluidity with a nontrivial Cooper-pairing, beyond the conventional Bardeen-Cooper-Schrieffer state, is a captivating field of study in quantum many-body systems. In particular, the search for superconducting states with finite-momentum pairs has long been a challenge, but establishing its existence has long suffered from the lack of an appropriate probe to reveal its momentum. Recently, it has been proposed that the nonreciprocal electron transport is the most powerful probe for the finite-momentum pairs, because it directly couples to the supercurrents. Here we reveal such a pairing state by the non-reciprocal transport on tricolor superlattices with strong spin-orbit coupling combined with broken inversion-symmetry consisting of atomically thin d-wave superconductor CeCoIn5. We find that while the second-harmonic resistance exhibits a distinct dip anomaly at the low-temperature (T)/high-magnetic field (H) corner in the HT-plane for H applied to the antinodal direction of the d-wave gap, such an anomaly is absent for H along the nodal direction. By carefully isolating extrinsic effects due to vortex dynamics, we reveal the presence of a non-reciprocal response originating from intrinsic superconducting properties characterized by finite-momentum pairs. We attribute the high-field state to the helical superconducting state, wherein the phase of the order parameter is spontaneously spatially modulated.
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Affiliation(s)
- T Asaba
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan.
| | - M Naritsuka
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
- RIKEN Center for Emergent Matter Science, Wako, Saitama, 351-0198, Japan
| | - H Asaeda
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Kosuge
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - S Ikemori
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - S Suetsugu
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Kasahara
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Kohsaka
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - T Terashima
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - A Daido
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Yanase
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto, 606-8502, Japan.
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Daido A, Ikeda Y, Yanase Y. Intrinsic Superconducting Diode Effect. PHYSICAL REVIEW LETTERS 2022; 128:037001. [PMID: 35119893 DOI: 10.1103/physrevlett.128.037001] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 12/08/2021] [Indexed: 05/28/2023]
Abstract
Stimulated by the recent experiment [F. Ando et al., Nature (London) 584, 373 (2020).NATUAS0028-083610.1038/s41586-020-2590-4], we propose an intrinsic mechanism to cause the superconducting diode effect (SDE). SDE refers to the nonreciprocity of the critical current for the metal-superconductor transition. Among various mechanisms for the critical current, the depairing current is known to be intrinsic to each material and has recently been observed in several superconducting systems. We clarify the temperature scaling of the nonreciprocal depairing current near the critical temperature and point out its significant enhancement at low temperatures. It is also found that the nonreciprocal critical current shows sign reversals upon increasing the magnetic field. These behaviors are understood by the nonreciprocity of the Landau critical momentum and the change in the nature of the helical superconductivity. The intrinsic SDE unveils the rich phase diagram and functionalities of noncentrosymmetric superconductors.
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Affiliation(s)
- Akito Daido
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yuhei Ikeda
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Youichi Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Institute for Molecular Science, Okazaki 444-8585, Japan
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