Anisotropic superconductivity and magnetism in single-crystal RbEuFe4As4

M. P. Smylie, K. Willa, J. K. Bao, K. Ryan, Z. Islam, H. Claus, Y. Simsek, Z. Diao, A. Rydh, A. E. Koshelev, W. K. Kwok, D. Y. Chung, Mercouri Kanatzidis, U. Welp

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18 Scopus citations

Abstract

We investigate the anisotropic superconducting and magnetic properties of single-crystal RbEuFe4As4 using magnetotransport and magnetization measurements. We determine a magnetic ordering temperature of the Eu moments of Tm=15K and a superconducting transition temperature of Tc=36.8K. The superconducting phase diagram is characterized by high upper critical field slopes of -70 and -42 kG/K for in-plane and out-of-plane fields, respectively, and a surprisingly low superconducting anisotropy of Γ=1.7. Ginzburg-Landau parameters of κc∼67 and κab∼108 indicate extreme type-II behavior. These superconducting properties are in line with those commonly seen in optimally doped Fe-based superconductors. In contrast, Eu magnetism is quasi-two dimensional (2D), as evidenced by highly anisotropic in-plane and out-of-plane exchange constants of 0.6 K and <0.04 K. A consequence of the quasi-2D nature of the Eu magnetism are strong magnetic fluctuation effects, a large suppression of the magnetic ordering temperature as compared to the Curie-Weiss temperature, and a kinklike anomaly in the specific heat devoid of any singularity. Magnetization curves reveal a clear magnetic easy-plane anisotropy with in-plane and out-of-plane saturation fields of 2 and 4 kG.

Original languageEnglish (US)
Article number104503
JournalPhysical Review B
Volume98
Issue number10
DOIs
StatePublished - Sep 5 2018

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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    Smylie, M. P., Willa, K., Bao, J. K., Ryan, K., Islam, Z., Claus, H., Simsek, Y., Diao, Z., Rydh, A., Koshelev, A. E., Kwok, W. K., Chung, D. Y., Kanatzidis, M., & Welp, U. (2018). Anisotropic superconductivity and magnetism in single-crystal RbEuFe4As4. Physical Review B, 98(10), [104503]. https://doi.org/10.1103/PhysRevB.98.104503