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

Tianzhen Zhang; Yining Hu; Wei Su; Chen Chen; Xu Wang; Dong Li; Zouyouwei Lu; Wentao Yang; Qingle Zhang; Xiaoli Dong; Rui Wang; Xiaoqun Wang; Donglai Feng; Tong Zhang

doi:10.1103/physrevlett.130.206001

arXiv · 2304.11939

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

Tianzhen Zhang·Yining Hu·Wei Su·Chen Chen·Xu Wang·Dong Li·Zouyouwei Lu·Wentao Yang·Qingle Zhang·Xiaoli Dong·Rui Wang·Xiaoqun Wang·Donglai Feng·Tong Zhang

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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.

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Tianzhen Zhang, Yining Hu, Wei Su, Chen Chen, Xu Wang, Dong Li, Zouyouwei Lu, Wentao Yang, Qingle Zhang, Xiaoli Dong, Rui Wang, Xiaoqun Wang, Donglai Feng, Tong Zhang. 2023-04-24. Phase shift and magnetic anisotropy induced field splitting of impurity states in (Li1-xFex)OHFeSe superconductor. https://doi.org/10.1103/physrevlett.130.206001

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