Spin excitation anisotropy as a probe of orbital ordering in the paramagnetic tetragonal phase of superconducting BaFe1.904Ni0.09As2

Huiqian Luo; Meng Wang; Chenglin Zhang; Xingye Lu; Louis-Pierre Regnault; Rui Zhang; Shiliang Li; Jiangping Hu; Pengcheng Dai

doi:10.1103/PhysRevLett.111.107006

Spin excitation anisotropy as a probe of orbital ordering in the paramagnetic tetragonal phase of superconducting BaFe1.904Ni0.09As2

Phys Rev Lett. 2013 Sep 6;111(10):107006. doi: 10.1103/PhysRevLett.111.107006. Epub 2013 Sep 5.

Authors

Huiqian Luo¹, Meng Wang¹, Chenglin Zhang², Xingye Lu¹, Louis-Pierre Regnault³, Rui Zhang¹, Shiliang Li¹, Jiangping Hu⁴, Pengcheng Dai⁵

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA and Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
³ SPSMS-MDN, UMR-E CEA/UJF-Grenoble 1, INAC, Grenoble, F-38054, France.
⁴ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA.
⁵ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China and Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA and Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA.

PMID: 25166700
DOI: 10.1103/PhysRevLett.111.107006

Abstract

We use polarized neutron scattering to demonstrate that in-plane spin excitations in electron doped superconducting BaFe1.904Ni0.096As2 (Tc=19.8 K) change from isotropic to anisotropic in the tetragonal phase well above the antiferromagnetic (AFM) ordering and tetragonal-to-orthorhombic lattice distortion temperatures (TN≈Ts=33±2 K) without an uniaxial pressure. While the anisotropic spin excitations are not sensitive to the AFM order and tetragonal-to-orthorhombic lattice distortion, superconductivity induces further anisotropy for spin excitations along the [110] and [110] directions. These results indicate that the spin excitation anisotropy is a probe of the electronic anisotropy or orbital ordering in the tetragonal phase of iron pnictides.