Campus Units

Physics and Astronomy, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

4-1-2011

Journal or Book Title

Physical Review B

Volume

83

Issue

13

First Page

134522

DOI

10.1103/PhysRevB.83.134522

Abstract

We present a combined high-resolution x-ray diffraction and x-ray resonant magnetic scattering study of as-grown BaFe2As2. The structural and magnetic transitions must be described as a two-step process. At TS = 134.5 K we observe the onset of a second-order structural transition from the high-temperature paramagnetic tetragonal structure to a paramagnetic orthorhombic phase, followed by a discontinuous step in the structural order parameter that is coincident with a first-order antiferromagnetic (AFM) transition at TN = 133.75 K. These data, together with detailed high-resolution x-ray studies of the structural transition in lightly doped Ba(Fe1−xCox)2As2 and Ba(Fe1−xRhx)2As2 compounds, show that the structural and AFM transitions do, in fact, occur at slightly different temperatures in the parent BaFe2As2 compound, and evolve toward split second-order transitions as the doping concentration is increased. We estimate the composition for the tricritical point for Co doping and employ a mean-field approach to show that our measurements can be explained by the inclusion of an anharmonic term in the elastic free energy and magnetoelastic coupling in the form of an emergent Ising-nematic degree of freedom.

Comments

This is an article published as Kim, M. G., R. M. Fernandes, A. Kreyssig, J. W. Kim, A. Thaler, S. L. Bud’ko, P. C. Canfield, R. J. McQueeney, J. Schmalian, and A. I. Goldman. "Character of the structural and magnetic phase transitions in the parent and electron-doped BaFe 2 As 2 compounds." Physical Review B 83, no. 13 (2011): 134522. DOI: 10.1103/PhysRevB.83.134522. Posted with permission.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

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