Phase shift and magnetic anisotropy induced field splitting of impurity states in (Li1-xFex)OHFeSe superconductor

Abstract

Revealing the energy and spatial characteristics of impurity induced states in superconductors is essential for understanding their mechanism and fabricating new quantum state by manipulating impurities. Here by using high-resolution scanning tunneling microscopy/spectroscopy, we investigated the spatial distribution and magnetic field response of the impurity states in (Li1-xFex)OHFeSe. We detected two pairs of strong in-gap states on the "dumbbell" shaped defects. They display clear damped oscillations with different phase shifts and a direct phase-energy correlation. These features have long been predicted for classical Yu-Shiba-Rusinov (YSR) state, which are demonstrated here with unprecedented resolution for the first time. Moreover, upon applying magnetic field, all the in-gap state peaks remarkably split into two rather than shift, and the splitting strength is field orientation dependent. Via detailed numerical model calculations, we found such anisotropic splitting behavior can be naturally induced by a high-spin impurity coupled to anisotropic environment, highlighting how magnetic anisotropy affects the behavior of YSR states.

Main text with supplementary (accepted by Phys. Rev. Lett.)

References in corpus (8)

• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Orbital Picture of Yu-Shiba-Rusinov Multiplets
• Soft chemical control of superconductivity in lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe
• Quantized conductance of Majorana zero mode in the vortex of the topological superconductor (Li0.84Fe0.16)OHFeSe
• Magnetic anisotropy effects on quantum impurities in superconducting host
• Superconducting (Li, Fe)OHFeSe film of high quality and high critical parameters
• Zeeman effects on Yu-Shiba-Rusinov states
• Quasi two-dimensional nature of high-Tc superconductivity in iron-based (Li,Fe)OHFeSe

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