[Paper] Magnetic edge fields in UTe$_2$ near zero background fields
Our new study about imaging the magnetic edge fields in chiral superconductor candidate UTe$_2$ was published in Physical Review B on December 4, 2024.
Chiral superconductivity is a rare and fascinating state of matter associated with spontaneous topological edge currents and other exotic phenomena. While time-reversal symmetry breaking has been observed in some superconductors, direct evidence for chiral edge currents remains absent. In this study, we used scanning SQUID microscopy with micron-scale resolution to investigate the magnetic fields near the edges of spin-triplet superconductor UTe$_2$, a candidate chiral superconductor. Our measurements revealed localized magnetic flux near sample edges at almost zero background field, consistent in magnitude with phenomenological predictions for the chiral superconductivity. However, we observed no multi-domain structures typically associated with chiral superconductivity.
Our findings suggest that the edge magnetic fields are not intrinsic but are extrinsically induced Meissner currents driven by hidden magnetic fields in the material. This interpretation aligns with recent polar Kerr and muon spin relaxation experiments on clean, single-transition samples of UTe$_2$, which report no evidence of spontaneous magnetization. These results support the view that UTe$_2$ may host single-component superconductivity at ambient pressure, contrasting with earlier claims of chiral behavior.
By uncovering the role of hidden magnetic fields in edge phenomena, this work provides new constraints on the superconducting order parameter of UTe$_2$. It highlights the interplay between extrinsic effects and intrinsic superconducting properties.
Magnetic edge fields in UTe2
near zero background fields
Y. Iguchi, H. Man, S. M. Thomas, F. Ronning, J.
Ishizuka, M. Sigrist, P.F.S. Rosa, and K. A. Moler
Physical Review B 110, 214505 (2024)