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Anomalies of upper critical field in the spinel superconductor LiTi2 O4-δ

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journal contribution
posted on 2020-02-10, 15:08 authored by Z Wei, G He, W Hu, Z Feng, X Wei, Q Li, J Yuan, Anna KusmartsevaAnna Kusmartseva, C Xi, Z Wang, Q Chen, B Zhu, F Zhou, X Dong, L Pi, Feodor Kusmartsev, Z Zhao, K Jin
© 2019 American Physical Society. High-field electrical transport and point-contact tunneling spectroscopy are used to investigate superconducting properties of spinel oxide LiTi2O4-δ films with various oxygen contents. It is striking that although the superconducting transition temperature and energy gap are almost unchanged, an isotropic upper critical field Bc2 up to 26.0 T is observed in the oxygen-rich sample, which is more than twice the Bc2 of 11.3 T in the anoxic one. The change of the dominating pair-breaking mechanism from the orbital effect to the spin flip at Bc2 is achieved by tuning oxygen contents, which can be explained by the appearance of small Fermi pockets due to extra oxygen. Our paper provides deep understanding of the intrinsic relation between Bc2 and the complex Fermi surface, and contributes a promising way to enhance Bc2 for practical superconductors.

Funding

National Key Basic Research Program of China (2015CB921000, 2016YFA0300301, 2017YFA0302902, 2017YFA0303003 and 2018YFB0704102),

National Natural Science Foundation of China (11674374, 11804378 and 11834016)

Strategic Priority Research Program of Chinese Academy of Sciences (XDB25000000),

Key Research Program of Frontier Sciences, CAS (QYZDB-SSW-SLH008 and QYZDY-SSW-SLH001)

History

School

  • Science

Department

  • Physics

Published in

Physical Review B

Volume

100

Issue

18

Pages

(5)

Publisher

American Physical Society

Version

  • VoR (Version of Record)

Rights holder

© American Physical Society

Publisher statement

This paper was published in the journal Physical Review B and the definitive published version is available at https://doi.org/10.1103/PhysRevB.100.184509

Publication date

2019-11-13

Copyright date

2019

ISSN

2469-9950

eISSN

2469-9969

Language

  • en

Depositor

Prof Fedor Kusmartsev . Deposit date: 9 February 2020

Article number

184509