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Anisotropic Hc2 of K0.8Fe1.76Se2 determined up to 60 T

E. D. Mun, M. M. Altarawneh, C. H. Mielke, V. S. Zapf, R. Hu, S. L. Bud’ko, and P. C. Canfield
Phys. Rev. B 83, 100514(R) – Published 30 March 2011

Abstract

The anisotropic upper critical field, Hc2(T), curves for K0.8Fe1.76Se2 are determined over a wide range of temperatures down to 1.5 K and magnetic fields up to 60 T. Anisotropic initial slopes of Hc2 ~ 1.4 T/K and 4.6 T/K for magnetic field applied along c axis and ab plane, respectively, were observed. Whereas the c axis Hc2c (T) increases quasilinearly with decreasing temperature, the ab plane Hc2ab(T) shows a flattening, starting near 25 K above 30 T. This leads to a nonmonotonic temperature dependence of the anisotropy parameter γH Hc2ab/Hc2c. The anisotropy parameter is ~2 near Tc~32 K and rises to a maximum γH~ 3.6 around 27 K. For lower temperatures, γH decreases with T in a linear fashion, dropping to γH~2.5 by T~18 K. Despite the apparent differences between the K0.8Fe1.76Se2 and (Ba0.55K0.45)Fe2As2 or Ba(Fe0.926Co0.074)2As2, in terms of the magnetic state and proximity to an insulating state, the Hc2(T) curves are remarkably similar.

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  • Received 2 March 2011

DOI:https://doi.org/10.1103/PhysRevB.83.100514

©2011 American Physical Society

Authors & Affiliations

E. D. Mun, M. M. Altarawneh, C. H. Mielke, and V. S. Zapf

  • National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

R. Hu, S. L. Bud’ko, and P. C. Canfield

  • Ames Laboratory, US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA

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Issue

Vol. 83, Iss. 10 — 1 March 2011

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