The radio-frequency spectra of ultracold Fermi atoms are calculated by including final-state interactions affecting the excited level of the transition and compared with the experimental data. A competition is revealed between pairing-gap effects which tend to push the oscillator strength toward high frequencies away from threshold and final-state effects which tend instead to pull the oscillator strength toward threshold. As a result of this competition, the position of the peak of the spectra cannot be simply related to the value of the pairing gap, whose extraction thus requires support from theoretical calculations.
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http://dx.doi.org/10.1103/PhysRevLett.100.010402 | DOI Listing |
Nat Mater
December 2024
Department of Physics, Southern University of Science and Technology, Shenzhen, China.
Superconductivity and magnetism are often antagonistic in quantum matter, although their intertwining has long been considered in frustrated-lattice systems. Here we utilize scanning tunnelling microscopy and muon spin resonance to demonstrate time-reversal symmetry-breaking superconductivity in kagome metal Cs(V, Ta)Sb, where the Cooper pairing exhibits magnetism and is modulated by it. In the magnetic channel, we observe spontaneous internal magnetism in a fully gapped superconducting state.
View Article and Find Full Text PDFPhys Rev Lett
June 2024
Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
We demonstrate that astrophysical constraints on the dense-matter equation of state place an upper bound on the color-superconducting gap in dense matter above the transition from nuclear matter to quark matter. Pairing effects in the color-flavor locked quark matter phase increase the pressure at high density, and if this effect is sufficiently large then the requirements of causality and mechanical stability make it impossible to reach such a pressure in a way that is consistent with what is known at lower densities. The intermediate-density equation of state is inferred by considering extensions of chiral effective field theory to neutron star densities, and conditioning these using current astrophysical observations of neutron star radius, maximum mass, and tidal deformability (PSR J0348+0432, PSR J1624-2230, PSR J0740+6620, GW170817).
View Article and Find Full Text PDFNature
February 2024
Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei, China.
The microscopic origin of high-temperature superconductivity in cuprates remains unknown. It is widely believed that substantial progress could be achieved by better understanding of the pseudogap phase, a normal non-superconducting state of cuprates. In particular, a central issue is whether the pseudogap could originate from strong pairing fluctuations.
View Article and Find Full Text PDFPhys Rev Lett
March 2023
Institute for Advanced Study, Tsinghua University, Beijing 100084, China.
We theoretically explore possible orders induced by weak repulsive interactions in twisted bilayer transition metal dichalcogenides (e.g., WSe_{2}) in the presence of an out-of-plane electric field.
View Article and Find Full Text PDFNano Lett
November 2022
Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah84112, United States.
Topological superconductivity (TSC) has drawn much attention for its fundamental interest and application in quantum computation. An outstanding challenge is the lack of intrinsic TSC materials with a -wave pairing gap, which has led to the development of an effective -wave theory of coupling -wave gap with Rashba spin-orbit coupling (RSOC). However, the RSOC-strict mechanism and materials pose still both fundamental and practical limitations.
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