Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

# Visualization of electron nematicity and unidirectional antiferroic fluctuations at high temperatures in NaFeAs

## Abstract

Superconductivity in the iron pnictides is often closely connected to a nematic state in which the tetragonal symmetry of the crystal is spontaneously broken. Determining the dominant interactions responsible for this symmetry breaking is essential to understanding the superconducting state. Here, we use atomic-resolution variable-temperature scanning tunnelling spectroscopy to probe the nanoscale electronic structure of the nematically ordered, parent pnictide NaFeAs and compare it with non-nematic LiFeAs. Local electronic nematicity is only manifest in NaFeAs and is found to persist to high temperatures in the nominally tetragonal phase of the crystal. The spatial distribution and energy dependence of the electronic anisotropy at high temperatures is explained by the persistence of large-amplitude, short-range, unidirectional, antiferroic fluctuations, indicating that strong density-wave fluctuations exist and couple to near-Fermi surface electrons even far from the structural and density-wave phase boundaries.

Your institute does not have access to this article

## Relevant articles

Open Access articles citing this article.

• ### Incommensurate smectic phase in close proximity to the high-Tc superconductor FeSe/SrTiO3

Nature Communications Open Access 13 April 2021

• ### Observation of an electronic order along [110] direction in FeSe

Nature Communications Open Access 02 March 2021

• ### Spatially dispersing Yu-Shiba-Rusinov states in the unconventional superconductor FeTe0.55Se0.45

Nature Communications Open Access 12 January 2021

## Access options

Buy article

Get time limited or full article access on ReadCube.

\$32.00

All prices are NET prices.

## References

1. Scalapino, D. J. A common thread: The pairing interaction for unconventional superconductors. Rev. Mod. Phys. 84, 1383–1417 (2012).

2. Wang, F. & Lee, D. H. The electron-pairing mechanism of iron-based superconductors. Science 332, 200–204 (2011).

3. Basov, D. N. & Chubukov, A. V. Manifesto for a higher Tc . Nature Phys. 7, 272–276 (2011).

4. Johnston, D. C. The puzzle of high temperature superconductivity in layered iron pnictides and chalcogenides. Adv. Phys. 59, 803–1061 (2010).

5. Yi, M. et al. Symmetry-breaking orbital anisotropy observed for detwinned Ba(Fe1−xCox)2As2 above the spin density wave transition. Proc. Natl Acad. Sci. USA 108, 6878–6883 (2011).

6. De la Cruz, C. et al. Magnetic order close to superconductivity in the iron-based layered LaO(1−x)F(x)FeAs systems. Nature 453, 899–902 (2008).

7. Fernandes, R. M. et al. Unconventional pairing in the iron arsenide superconductors. Phys. Rev. B 81, 140501(R) (2010).

8. Nandi, S. et al. Anomalous suppression of the orthorhombic lattice distortion in superconducting Ba(Fe1−xCox)2As2 single crystals. Phys. Rev. Lett. 104, 057006 (2010).

9. Chu, J. H. et al. In-plane resistivity anisotropy in an underdoped iron arsenide superconductor. Science 329, 824–826 (2010).

10. Tanatar, M. A. et al. Uniaxial-strain mechanical detwinning of CaFe2As2 and BaFe2As2 crystals: Optical and transport study. Phys. Rev. B 81, 184508 (2010).

11. Kasahara, S. et al. Electronic nematicity above the structural and superconducting transition in BaFe2(As1−xPx)2 . Nature 486, 382–385 (2012).

12. Chu, J. H., Kuo, H. H., Analytis, J. G. & Fisher, I. R. Divergent nematic susceptibility in an iron arsenide superconductor. Science 337, 710–712 (2012).

13. Gallais, Y. et al. Observation of incipient charge nematicity in Ba(Fe1−xCox)2As2 . Phys. Rev. Lett. 111, 267001 (2013).

14. Dusza, A. et al. Anisotropic charge dynamics in detwinned Ba(Fe1−xCox)2As2 . Europhys. Lett. 93, 37002 (2011).

15. Nakajima, M. et al. Unprecedented anisotropic metallic state in undoped iron arsenide BaFe2As2 revealed by optical spectroscopy. Proc. Natl Acad. Sci. USA 108, 12238–12242 (2011).

16. Dhital, C. et al. Effect of uniaxial strain on the structural and magnetic phase transitions in BaFe2As2 . Phys. Rev. Lett. 108, 087001 (2012).

17. Fang, C., Yao, H., Tsai, W. F., Hu, J. P. & Kivelson, S. A. Theory of electron nematic order in LaFeAsO. Phys. Rev. B 77, 224509 (2008).

18. Xu, C., Muller, M. & Sachdev, S. Ising and spin orders in the iron-based superconductors. Phys. Rev. B 78, 020501(R) (2008).

19. Mazin, I. I. & Johannes, M. D. A key role for unusual spin dynamics in ferropnictides. Nature Phys. 5, 141–145 (2009).

20. Fernandes, R. M., Abrahams, E. & Schmalian, J. Anisotropic in-plane resistivity in the nematic phase of the iron pnictides. Phys. Rev. Lett. 107, 217002 (2011).

21. Fernandes, R. M., Chubukov, A. V., Knolle, J., Eremin, I. & Schmalian, J. Preemptive nematic order, pseudogap, and orbital order in the iron pnictides. Phys. Rev. B 85, 024534 (2012).

22. Lv, W. C. & Phillips, P. Orbitally and magnetically induced anisotropy in iron-based superconductors. Phys. Rev. B 84, 174512 (2011).

23. Chen, C. C. et al. Orbital order and spontaneous orthorhombicity in iron pnictides. Phys. Rev. B 82, 100504(R) (2010).

24. Kontani, H., Saito, T. & Onari, S. Origin of orthorhombic transition, magnetic transition, and shear-modulus softening in iron pnictide superconductors: Analysis based on the orbital fluctuations theory. Phys. Rev. B 84, 024528 (2011).

25. Song, C. L. et al. Direct observation of nodes and twofold symmetry in FeSe superconductor. Science 332, 1410–1413 (2011).

26. Chuang, T. M. et al. Nematic electronic structure in the ‘Parent’ state of the iron-based superconductor Ca(Fe1−xCox)2As2 . Science 327, 181–184 (2010).

27. Zhou, X. D. et al. Quasiparticle interference of C2-symmetric surface states in a LaOFeAs parent compound. Phys. Rev. Lett. 106, 087001 (2011).

28. Zhou, X. D. et al. Evolution from unconventional spin density wave to superconductivity and a pseudogaplike phase in NaFe1−xCoxAs. Phys. Rev. Lett. 109, 037002 (2012).

29. Hanke, T. et al. Probing the unconventional superconducting state of LiFeAs by quasiparticle interference. Phys. Rev. Lett. 108, 127001 (2012).

30. Allan, M. P. et al. Anisotropic energy gaps of iron-based superconductivity from intraband quasiparticle interference in LiFeAs. Science 336, 563–567 (2012).

31. Hanaguri, T. et al. Scanning tunneling microscopy/spectroscopy of vortices in LiFeAs. Phys. Rev. B 85, 214505 (2012).

32. Grothe, S. et al. Bound states of defects in superconducting LiFeAs studied by scanning tunneling spectroscopy. Phys. Rev. B. 86, 174503 (2012).

33. Wang, X. C. et al. The superconductivity at 18 K in LiFeAs system. Solid State Commun. 148, 538–540 (2008).

34. Tapp, J. H. et al. LiFeAs: An intrinsic FeAs-based superconductor with Tc = 18 K. Phys. Rev. B 78, 060505(R) (2008).

35. Chu, C. W. et al. The synthesis and characterization of LiFeAs and NaFeAs. Physica C 469, 326–331 (2009).

36. Kalisky, B. et al. Stripes of increased diamagnetic susceptibility in underdoped superconducting Ba(Fe(1−x)Cox)2As2 single crystals: Evidence for an enhanced superfluid density at twin boundaries. Phys. Rev. B 81, 184513 (2010).

37. Allan, M. P. et al. Anisotropic impurity states, quasiparticle scattering and nematic transport in underdoped Ca(Fe1−xCox)2As2 . Nature Phys. 9, 220–224 (2013).

38. Knolle, J., Eremin, I., Akbari, A. & Moessner, R. Quasiparticle interference in the spin-density wave phase of iron-based superconductors. Phys. Rev. Lett. 104, 257001 (2010).

39. Crommie, M. F., Lutz, C. P. & Eigler, D. M. Imaging standing waves in a two-dimensional electron gas. Nature 363, 524–527 (1993).

40. Yi, M. et al. Electronic reconstruction through the structural and magnetic transitions in detwinned NaFeAs. New J. Phys. 14, 073019 (2012).

41. Zhang, Y. et al. Symmetry breaking via orbital-dependent reconstruction of electronic structure in detwinned NaFeAs. Phys. Rev. B 85, 085121 (2012).

42. Wang, A. F. et al. A crossover in the phase diagram of NaFe1−xCoxAs determined by electronic transport measurements. New J. Phys. 15, 043048 (2013).

43. Wang, Q. H. & Lee, D. H. Quasiparticle scattering interference in high-temperature superconductors. Phys. Rev. B 67, 020511(R) (2003).

44. Chatterjee, U. et al. Nondispersive fermi arcs and the absence of charge ordering in the pseudogap phase of Bi2Sr2CaCu2O8+δ . Phys. Rev. Lett. 96, 107006 (2006).

45. Ran, Y., Wang, F., Zhai, H., Vishwanath, A. & Lee, D. H. Nodal spin density wave and band topology of the FeAs-based materials. Phys. Rev. B 79, 014505 (2009).

46. Lee, P. A., Rice, T. M. & Anderson, P. W. Fluctuation effects at a Peierls transition. Phys. Rev. Lett. 31, 462–465 (1973).

47. Park, J. T. et al. Similar zone-center gaps in the low-energy spin-wave spectra of Na1−δ FeAs and BaFe2As2 . Phys. Rev. B 86, 024437 (2012).

48. Ma, L. et al. Na-23 and As-75 NMR study of antiferromagnetism and spin fluctuations in NaFeAs single crystals. Phys. Rev. B 83, 132501 (2011).

49. Maeter, H. et al. Structural and electronic phase diagrams of CeFeAsO1−xFx and SmFeAsO1−xFx. Preprint at http://arxiv.org/abs/1210.6959 (2012)

50. Song, Y. et al. Uniaxial pressure effect on structural and magnetic phase transitions in NaFeAs and its comparison with as-grown and annealed BaFe2As2 . Phys. Rev. B 87, 184511 (2013).

Download references

## Acknowledgements

We thank L. Zhao and C. Gutierrez for experimental help and T. Giamarchi and I. Eremin for discussions. We thank M. Yi and Z-X. Shen for sharing ARPES data on NaFeAs. This work is supported by the National Science Foundation through the Partnerships for International Research and Education grant no. OISE-0968226 and Defense Advanced Research Projects Agency grant no. N66001-12-1-4216 (A.N.P. and E.P.R.). Equipment support is provided by the Air Force Office for Scientific Research under grant no. FA9550-11-1-0010. Support is also provided by the National Science Foundation through grant no. NSF-DMR 1006282 (A.J.M.) and the National Science Foundation of China and Ministry of Science and Technology of China (L.Y.X., X.C.W. and C.Q.J.).

## Author information

Authors

### Contributions

STM experiments and data analysis: E.P.R., E.F.A., C.J.A. and A.N.P. Theoretical analysis: R.M.F. and A.J.M. Sample synthesis and characterization: L.Y.X., X.C.W. and C.Q.J. All authors participated in writing the manuscript.

### Corresponding author

Correspondence to A. N. Pasupathy.

## Ethics declarations

### Competing interests

The authors declare no competing financial interests.

## Supplementary information

### Supplementary Information

Supplementary Information (PDF 721 kb)

### Supplementary Movie

Supplementary Movie 2 (MP4 3983 kb)

### Supplementary Movie

Supplementary Movie 3 (MP4 2716 kb)

### Supplementary Movie

Supplementary Movie 4 (MP4 2762 kb)

### Supplementary Movie

Supplementary Movie 5 (MP4 2638 kb)

### Supplementary Movie

Supplementary Movie 6 (MP4 2671 kb)

### Supplementary Movie

Supplementary Movie 7 (MP4 2894 kb)

## Rights and permissions

Reprints and Permissions

## About this article

### Cite this article

Rosenthal, E., Andrade, E., Arguello, C. et al. Visualization of electron nematicity and unidirectional antiferroic fluctuations at high temperatures in NaFeAs. Nature Phys 10, 225–232 (2014). https://doi.org/10.1038/nphys2870

Download citation

• Received:

• Accepted:

• Published:

• Issue Date:

• DOI: https://doi.org/10.1038/nphys2870

## Further reading

• ### Incommensurate smectic phase in close proximity to the high-Tc superconductor FeSe/SrTiO3

• Yonghao Yuan
• Xuemin Fan
• Wei Li

Nature Communications (2021)

• ### Observation of an electronic order along [110] direction in FeSe

• Kunliang Bu
• Wenhao Zhang
• Yi Yin

Nature Communications (2021)

• ### Nematic transition and nanoscale suppression of superconductivity in Fe(Te,Se)

• He Zhao
• Hong Li
• Ilija Zeljkovic

Nature Physics (2021)

• ### Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

• Zheng Ren
• Hong Li
• Ilija Zeljkovic

Nature Communications (2021)

• ### Spatially dispersing Yu-Shiba-Rusinov states in the unconventional superconductor FeTe0.55Se0.45

• Damianos Chatzopoulos
• Doohee Cho
• Milan P. Allan

Nature Communications (2021)

## Search

### Quick links

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing