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Devarakonda A, Chen A, Fang S, Graf D, Kriener M, Akey AJ, Bell DC, Suzuki T, Checkelsky JG. Evidence of striped electronic phases in a structurally modulated superlattice. Nature 2024; 631:526-530. [PMID: 38961299 DOI: 10.1038/s41586-024-07589-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 05/21/2024] [Indexed: 07/05/2024]
Abstract
The electronic properties of crystals can be manipulated by superimposing spatially periodic electric, magnetic or structural modulations. Long-wavelength modulations incommensurate with the atomic lattice are particularly interesting1, exemplified by recent advances in two-dimensional (2D) moiré materials2,3. Bulk van der Waals (vdW) superlattices4-8 hosting 2D interfaces between minimally disordered layers represent scalable bulk analogues of artificial vdW heterostructures and present a complementary venue to explore incommensurately modulated 2D states. Here we report the bulk vdW superlattice SrTa2S5 realizing an incommensurate one-dimensional (1D) structural modulation of 2D transition metal dichalcogenide (TMD) H-TaS2 layers. High-quality electronic transport in the H-TaS2 layers, evidenced by quantum oscillations, is made anisotropic by the modulation and exhibits commensurability oscillations paralleling lithographically modulated 2D systems9-11. We also find unconventional, clean-limit superconductivity in SrTa2S5 with a pronounced suppression of interlayer relative to intralayer coherence. The in-plane magnetic field dependence of interlayer critical current, together with electron diffraction from the structural modulation, suggests superconductivity12-14 in SrTa2S5 is spatially modulated and mismatched between adjacent TMD layers. With phenomenology suggestive of pair-density wave superconductivity15-17, SrTa2S5 may present a pathway for microscopic evaluation of this unconventional order18-21. More broadly, SrTa2S5 establishes bulk vdW superlattices as versatile platforms to address long-standing predictions surrounding modulated electronic phases in the form of nanoscale vdW devices12,13 to macroscopic crystals22,23.
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Affiliation(s)
- A Devarakonda
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
| | - A Chen
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - S Fang
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - D Graf
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - M Kriener
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - A J Akey
- Center for Nanoscale Systems, Harvard University, Cambridge, MA, USA
| | - D C Bell
- Center for Nanoscale Systems, Harvard University, Cambridge, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - T Suzuki
- Department of Physics, Toho University, Funabashi, Japan
| | - J G Checkelsky
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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2
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Wan P, Zheliuk O, Yuan NFQ, Peng X, Zhang L, Liang M, Zeitler U, Wiedmann S, Hussey NE, Palstra TTM, Ye J. Orbital Fulde-Ferrell-Larkin-Ovchinnikov state in an Ising superconductor. Nature 2023:10.1038/s41586-023-05967-z. [PMID: 37225992 DOI: 10.1038/s41586-023-05967-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/17/2023] [Indexed: 05/26/2023]
Abstract
In superconductors possessing both time and inversion symmetries, the Zeeman effect of an external magnetic field can break the time-reversal symmetry, forming a conventional Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state characterized by Cooper pairings with finite momentum1,2. In superconductors lacking (local) inversion symmetry, the Zeeman effect may still act as the underlying mechanism of FFLO states by interacting with spin-orbit coupling (SOC). Specifically, the interplay between the Zeeman effect and Rashba SOC can lead to the formation of more accessible Rashba FFLO states that cover broader regions in the phase diagram3-5. However, when the Zeeman effect is suppressed because of spin locking in the presence of Ising-type SOC, the conventional FFLO scenarios are no longer effective. Instead, an unconventional FFLO state is formed by coupling the orbital effect of magnetic fields with SOC, providing an alternative mechanism in superconductors with broken inversion symmetries6-8. Here we report the discovery of such an orbital FFLO state in the multilayer Ising superconductor 2H-NbSe2. Transport measurements show that the translational and rotational symmetries are broken in the orbital FFLO state, providing the hallmark signatures of finite-momentum Cooper pairings. We establish the entire orbital FFLO phase diagram, consisting of a normal metal, a uniform Ising superconducting phase and a six-fold orbital FFLO state. This study highlights an alternative route to achieving finite-momentum superconductivity and provides a universal mechanism to preparing orbital FFLO states in similar materials with broken inversion symmetries.
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Affiliation(s)
- Puhua Wan
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Oleksandr Zheliuk
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - Noah F Q Yuan
- School of Science, Harbin Institute of Technology, Shenzhen, China
| | - Xiaoli Peng
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Le Zhang
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Minpeng Liang
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Uli Zeitler
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - Steffen Wiedmann
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - Nigel E Hussey
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
- H. H. Wills Physics Laboratory, University of Bristol, Bristol, UK
| | - Thomas T M Palstra
- Nano Electronic Materials, University of Twente, Enschede, The Netherlands
| | - Jianting Ye
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
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3
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Sahu SK, Mandal S, Ghosh S, Deshmukh MM, Singh V. Superconducting Vortex-Charge Measurement Using Cavity Electromechanics. NANO LETTERS 2022; 22:1665-1671. [PMID: 35147441 DOI: 10.1021/acs.nanolett.1c04688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
As the magnetic field penetrates the surface of a superconductor, it results in the formation of flux vortices. It has been predicted that the flux vortices will have a charged vortex core and create a dipolelike electric field. Such a charge trapping in vortices is particularly enhanced in high-Tc superconductors (HTS). Here, we integrate a mechanical resonator made of a thin flake of HTS Bi2Sr2CaCu2O8+δ into a microwave circuit to realize a cavity-electromechanical device. Due to the exquisite sensitivity of cavity-based devices to the external forces, we directly detect the charges in the flux vortices by measuring the electromechanical response of the mechanical resonator. Our measurements reveal the strength of surface electric dipole moment due to a single vortex core to be approximately 30 |e|aB, equivalent to a vortex charge per CuO2 layer of 3.7 × 10-2|e|, where aB is the Bohr radius and e is the electronic charge.
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Affiliation(s)
- Sudhir Kumar Sahu
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Supriya Mandal
- Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Sanat Ghosh
- Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Mandar M Deshmukh
- Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Vibhor Singh
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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