Anisotropic upper critical field of pristine and proton-irradiated single crystals of the magnetically ordered superconductor RbEuFe4 As4

M. P. Smylie, A. E. Koshelev, K. Willa, R. Willa, W. K. Kwok, J. K. Bao, D. Y. Chung, M. G. Kanatzidis, J. Singleton, F. F. Balakirev, H. Hebbeker, P. Niraula, E. Bokari, A. Kayani, U. Welp

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We present a study of the upper critical field Hc2 of pristine and proton-irradiated RbEuFe4As4 crystals in pulsed magnetic fields of up to 65 T. The data for Hc2 reveal pronounced downwards curvature, particularly for the in-plane field orientation, and a superconducting anisotropy that decreases with decreasing temperature. These features are indicative of Pauli paramagnetic limiting. For the interpretation of these data, we use a model of a clean single-band superconductor with an open Fermi surface in the shape of a warped cylinder, which takes into account Zeeman spin splitting. Fits to the data reveal that the in-plane upper critical field is Pauli paramagnetic limited, while the out-of-plane upper critical field is orbitally limited and that the orbital and paramagnetic fields have opposite anisotropies. A consequence of this particular combination is the unusual inversion of the anisotropy Hc2ab<Hc2c of the irradiated sample at temperatures below 10 K. The fits also yield an in-plane Maki parameter αM110≈2.6 exceeding the critical value for the formation of the Fulde-Ferrell-Larkin-Ovchinnikov state. Nevertheless, the current measurements did not reveal direct evidence for the occurrence of this state.

Original languageEnglish
Article number054507
JournalPhysical Review B
Volume100
Issue number5
DOIs
Publication statusPublished - Aug 7 2019

    Fingerprint

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Smylie, M. P., Koshelev, A. E., Willa, K., Willa, R., Kwok, W. K., Bao, J. K., Chung, D. Y., Kanatzidis, M. G., Singleton, J., Balakirev, F. F., Hebbeker, H., Niraula, P., Bokari, E., Kayani, A., & Welp, U. (2019). Anisotropic upper critical field of pristine and proton-irradiated single crystals of the magnetically ordered superconductor RbEuFe4 As4. Physical Review B, 100(5), [054507]. https://doi.org/10.1103/PhysRevB.100.054507