Dynamic Spin-Lattice Coupling and Nematic Fluctuations in NaFeAs

Yu Li; Zahra Yamani; Yu Song; Weiyi Wang; Chenglin Zhang; David W. Tam; Tong Chen; Ding Hu; Zhuang Xu; Songxue Chi; Ke Xia; Li Zhang; Shifeng Cui; Wenan Guo; Ziming Fang; Yi Liu; Pengcheng Dai

doi:10.1103/PhysRevX.8.021056

Dynamic Spin-Lattice Coupling and Nematic Fluctuations in NaFeAs

Yu Li, Zahra Yamani, Yu Song, Weiyi Wang, Chenglin Zhang, David W. Tam, Tong Chen, Ding Hu, Zhuang Xu, Songxue Chi, Ke Xia, Li Zhang, Shifeng Cui, Wenan Guo, Ziming Fang, Yi Liu, Pengcheng Dai

Spectroscopy

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron-pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at Ts≈58 K and a collinear antiferromagnetic order at TN≈45 K. While longitudinal and out-of-plane transverse acoustic phonons behave as expected, the in-plane transverse acoustic phonons reveal considerable softening on cooling to Ts and then harden on approaching TN before saturating below TN. In addition, we find that spin-spin correlation lengths of low-energy magnetic excitations within the FeAs layer and along the c axis increase dramatically below Ts and show a weak anomaly across TN. These results suggest that the electronic nematic phase present in the paramagnetic tetragonal phase is closely associated with dynamic spin-lattice coupling, possibly arising from the one-phonon-two-magnon mechanism.

Original language	English
Article number	021056
Journal	Physical Review X
Volume	8
Issue number	2
DOIs	https://doi.org/10.1103/PhysRevX.8.021056
State	Published - Jun 1 2018

Funding

We thank Rong Yu and Qimiao Si for helpful discussions. The single crystal growth and neutron scattering work at Rice is supported by the U.S. DOE, BES under Contract No. DE-SC0012311 (P. D.). Part of the materials work at Rice is supported by the Robert A. Welch Foundation Grant No. C-1839 (P. D.). The DFT calculation was partly supported by the National Natural Science Foundation of China (Grant No. 61604013) and the Fundamental Research Funds for the Central Universities (Grant No. 2016NT10). K. X. is supported by the National Key R&D Program of China (2017YFA0303300) and NSFC (11734004, 61774017, and 21421003). W. A. G is supported by NSFC 11775021 and 11734002. This research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.

Funders	Funder number
U.S. Department of Energy
Welch Foundation	C-1839
Welch Foundation
Basic Energy Sciences	DE-SC0012311
Basic Energy Sciences
National Natural Science Foundation of China	11734004, 21421003, 61604013, 11734002, 61774017, 11775021
National Natural Science Foundation of China
National Key Research and Development Program of China	2017YFA0303300
National Key Research and Development Program of China
Fundamental Research Funds for the Central Universities	2016NT10
Fundamental Research Funds for the Central Universities

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title = "Dynamic Spin-Lattice Coupling and Nematic Fluctuations in NaFeAs",

abstract = "We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron-pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at Ts≈58 K and a collinear antiferromagnetic order at TN≈45 K. While longitudinal and out-of-plane transverse acoustic phonons behave as expected, the in-plane transverse acoustic phonons reveal considerable softening on cooling to Ts and then harden on approaching TN before saturating below TN. In addition, we find that spin-spin correlation lengths of low-energy magnetic excitations within the FeAs layer and along the c axis increase dramatically below Ts and show a weak anomaly across TN. These results suggest that the electronic nematic phase present in the paramagnetic tetragonal phase is closely associated with dynamic spin-lattice coupling, possibly arising from the one-phonon-two-magnon mechanism.",

author = "Yu Li and Zahra Yamani and Yu Song and Weiyi Wang and Chenglin Zhang and Tam, {David W.} and Tong Chen and Ding Hu and Zhuang Xu and Songxue Chi and Ke Xia and Li Zhang and Shifeng Cui and Wenan Guo and Ziming Fang and Yi Liu and Pengcheng Dai",

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AU - Li, Yu

AU - Yamani, Zahra

AU - Song, Yu

AU - Wang, Weiyi

AU - Zhang, Chenglin

AU - Tam, David W.

AU - Chen, Tong

AU - Hu, Ding

AU - Xu, Zhuang

AU - Chi, Songxue

AU - Xia, Ke

AU - Zhang, Li

AU - Cui, Shifeng

AU - Guo, Wenan

AU - Fang, Ziming

AU - Liu, Yi

AU - Dai, Pengcheng

PY - 2018/6/1

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N2 - We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron-pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at Ts≈58 K and a collinear antiferromagnetic order at TN≈45 K. While longitudinal and out-of-plane transverse acoustic phonons behave as expected, the in-plane transverse acoustic phonons reveal considerable softening on cooling to Ts and then harden on approaching TN before saturating below TN. In addition, we find that spin-spin correlation lengths of low-energy magnetic excitations within the FeAs layer and along the c axis increase dramatically below Ts and show a weak anomaly across TN. These results suggest that the electronic nematic phase present in the paramagnetic tetragonal phase is closely associated with dynamic spin-lattice coupling, possibly arising from the one-phonon-two-magnon mechanism.

AB - We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron-pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at Ts≈58 K and a collinear antiferromagnetic order at TN≈45 K. While longitudinal and out-of-plane transverse acoustic phonons behave as expected, the in-plane transverse acoustic phonons reveal considerable softening on cooling to Ts and then harden on approaching TN before saturating below TN. In addition, we find that spin-spin correlation lengths of low-energy magnetic excitations within the FeAs layer and along the c axis increase dramatically below Ts and show a weak anomaly across TN. These results suggest that the electronic nematic phase present in the paramagnetic tetragonal phase is closely associated with dynamic spin-lattice coupling, possibly arising from the one-phonon-two-magnon mechanism.

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Dynamic Spin-Lattice Coupling and Nematic Fluctuations in NaFeAs

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