One of the most sought-after objects in topological quantum-matter systems is a vortex carrying half a quantum of circulation. They were originally predicted to exist in superfluid ^{3}He-A but have never been resolved there. Here we report an observation of half-quantum vortices (HQVs) in the polar phase of superfluid ^{3}He. The vortices are created with rotation or by the Kibble-Zurek mechanism and identified based on their nuclear magnetic resonance signature. This discovery provides a pathway for studies of unpaired Majorana modes bound to the HQV cores in the polar-distorted A phase.
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http://dx.doi.org/10.1103/PhysRevLett.117.255301 | DOI Listing |
J Phys Condens Matter
November 2024
University of Bordeaux, LOMA UMR-CNRS 5798, F-33405 Talence, France.
Recently, the use of circularly polarized radiation for on-demand switching between distinct quantum states in a superconducting nanoring exposed to half-quantum magnetic flux has been proposed. However, the effectiveness of this method depends on the system's stability against local variations in the superconducting characteristics of the ring and flux fluctuations. In this study, we utilize numerical simulations based on the time-dependent Ginzburg-Landau equation to evaluate the influence of these inevitable factors on the switching behavior.
View Article and Find Full Text PDFJ Phys Condens Matter
March 2023
Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
The different superfluid phases ofHe are described by-wave order parameters that include anisotropy axes both in the orbital and spin spaces. The anisotropy axes characterize the broken symmetries in these macroscopically coherent quantum many-body systems. The systems' free energy has several degenerate minima for certain orientations of the anisotropy axes.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2022
School of Physics and Astronomy and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom.
We report that high-quality single crystals of the hexagonal heavy fermion material uranium diauride (UAu) become superconducting at pressures above 3.2 GPa, the pressure at which an unusual antiferromagnetic state is suppressed. The antiferromagnetic state hosts a marginal fermi liquid and the pressure evolution of the resistivity within this state is found to be very different from that approaching a standard quantum phase transition.
View Article and Find Full Text PDFNat Commun
October 2022
Department of Physics, Princeton University, Princeton, NJ, 08544, USA.
In insulating crystals, it was previously shown that defects with two fewer dimensions than the bulk can bind topological electronic states. We here further extend the classification of topological defect states by demonstrating that the corners of crystalline defects with integer Burgers vectors can bind 0D higher-order end (HEND) states with anomalous charge and spin. We demonstrate that HEND states are intrinsic topological consequences of the bulk electronic structure and introduce new bulk topological invariants that are predictive of HEND dislocation states in solid-state materials.
View Article and Find Full Text PDFSci Adv
November 2021
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
Interfaces between materials with differently ordered phases present unique opportunities for exotic physical properties, especially the interplay between ferromagnetism and superconductivity in the ferromagnet/superconductor heterostructures. The investigation of zero- and π-junctions has been of particular interest for both fundamental physical science and emerging technologies. Here, we report the experimental observation of giant oscillatory Gilbert damping in the superconducting niobium/nickel-iron/niobium junctions with respect to the nickel-iron thickness.
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