Visualizing the finite-momentum pairing state in EuRbFe<sub>4</sub>As<sub>4</sub> via quasiparticle interference

Nonmagnetic superconductors are characterized by pairs of electrons with equal and opposite momenta. When superconductors are subjected to magnetic interactions, it has been hypothesized that they could feature pairs of electrons with nonzero total momentum, leading to a superconducting order parameter whose phase or amplitude is spatially modulated. In this work, we show evidence from Spectroscopic Imaging Scanning Tunneling Microscopy (SI-STM) that a phase-modulated superconducting order parameter exists in the magnetic (T_m ~ 15K) iron pnictide superconductor (T_c ~ 37K) EuRbFe₄As₄ (ER-1144). By utilizing the quasiparticle interference (QPI) imaging, we reveal that the magnetic superconducting state features gapless excitations of a Bogoliubov Fermi surface, which break the four-fold rotational (C₄) symmetry of the crystal lattice. In addition, temperature and field-dependent measurements reveal a recovery of the C₄ symmetry, demonstrating that the anisotropic Bogoliubov Fermi surface is closely tied to the crystal’s magnetic order. The observed anisotropy can be naturally explained by the unidirectional Doppler shift in the quasiparticle energies that is inherent to a phase-modulated superconductor.

*Work at Brookhaven is supported by the Office of Basic Energy Sciences, Materials Sciences and Engineering Division, US Department of Energy under contract no. DE-SC0012704. The work at AIST was supported by the Grant-in-Aid for Scientific Research on Innovative Areas 'Quantum Liquid Crystals' (KAKENHI grant no. JP19H05823) from JSPS of Japan

About APS

The American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics.

Headquarters 1 Physics Ellipse, College Park, MD 20740-3844 (301) 209-3200
Editorial Office 100 Motor Pkwy, Suite 110, Hauppauge, NY 11788 (631) 591-4000
Office of Public Affairs 529 14th St NW, Suite 1050, Washington, D.C. 20045-2001 (202) 662-8700

Bulletin of the American Physical Society

2024 APS March Meeting

Monday–Friday, March 4–8, 2024; Minneapolis & Virtual

Session D15: Superconductivity: Tunneling Properties

Abstract: D15.00003 : Visualizing the finite-momentum pairing state in EuRbFe4As4 via quasiparticle interference*

Presenter:

Authors:

Follow Us

Engage

My APS

Information for

About APS

Abstract: D15.00003 : Visualizing the finite-momentum pairing state in EuRbFe₄As₄ via quasiparticle interference*