In-plane uniaxial pressure-induced out-of-plane antiferromagnetic moment and critical fluctuations in BaFe2As2

Panpan Liu; Mason L Klemm; Long Tian; Xingye Lu; Yu Song; David W Tam; Karin Schmalzl; J T Park; Yu Li; Guotai Tan; Yixi Su; Frédéric Bourdarot; Yang Zhao; Jeffery W Lynn; Robert J Birgeneau; Pengcheng Dai

doi:10.1038/s41467-020-19421-5

In-plane uniaxial pressure-induced out-of-plane antiferromagnetic moment and critical fluctuations in BaFe₂As₂

Nat Commun. 2020 Nov 12;11(1):5728. doi: 10.1038/s41467-020-19421-5.

Authors

Panpan Liu¹, Mason L Klemm², Long Tian¹, Xingye Lu³, Yu Song⁴, David W Tam², Karin Schmalzl⁵, J T Park⁶, Yu Li², Guotai Tan¹, Yixi Su⁷, Frédéric Bourdarot⁸, Yang Zhao⁹, Jeffery W Lynn⁹, Robert J Birgeneau^{4

10

11}, Pengcheng Dai¹²

Affiliations

¹ Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, 100875, Beijing, China.
² Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.
³ Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, 100875, Beijing, China. luxy@bnu.edu.cn.
⁴ Department of Physics, University of California, Berkeley, CA, 94720, USA.
⁵ Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at ILL, 71 avenue des Martyrs, 38000, Grenoble, France.
⁶ Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, 85748, Garching, Germany.
⁷ Jülich Centre for Neutron Science JCNS at MLZ, Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747, Garching, Germany.
⁸ University Grenoble Alpes, CEA, IRIG, MEM-MDN, Grenoble, France.
⁹ NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
¹⁰ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
¹¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
¹² Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA. pdai@rice.edu.

Abstract

A small in-plane external uniaxial pressure has been widely used as an effective method to acquire single domain iron pnictide BaFe₂As₂, which exhibits twin-domains without uniaxial strain below the tetragonal-to-orthorhombic structural (nematic) transition temperature T_s. Although it is generally assumed that such a pressure will not affect the intrinsic electronic/magnetic properties of the system, it is known to enhance the antiferromagnetic (AF) ordering temperature T_N ( < T_s) and create in-plane resistivity anisotropy above T_s. Here we use neutron polarization analysis to show that such a strain on BaFe₂As₂ also induces a static or quasi-static out-of-plane (c-axis) AF order and its associated critical spin fluctuations near T_N/T_s. Therefore, uniaxial pressure necessary to detwin single crystals of BaFe₂As₂ actually rotates the easy axis of the collinear AF order near T_N/T_s, and such effects due to spin-orbit coupling must be taken into account to unveil the intrinsic electronic/magnetic properties of the system.

Grants and funding

C1839/Welch Foundation