skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Surface terminations and layer-resolved tunneling spectroscopy of the 122 iron pnictide superconductors

Abstract

The surface terminations of 122-type alkaline earth metal iron pnictides AEFe 2As 2( AE=Ca,Ba) are investigated with scanning tunneling microscopy/spectroscopy. Cleaving these crystals at a cryogenic temperature yields a large majority of terminations with an atomically resolved (√2 × √2)R45 or 1 × 2 lattice, as well as a very rare termination of 1 × 1 lattice symmetry. By assessing the lattice registration and selective chemical marking, we identify these terminations as (√2 × √2)R45-reconstructed AE, 1 × 2-reconstructed As, and (√2 × √2)R45-reconstructed Fe surface layers, respectively. Layer-resolved tunneling spectroscopy on these terminating surfaces reveals a well-defined superconducting energy gap on the As terminations, while the gap features become weaker on the AE terminations and absent on the Fe terminations. The superconducting gap is hardly affected locally by the As or AE surface reconstructions. The definitive identification of the surface terminations and the associated spectroscopic signatures shed light on the necessary roles of As and the pnictogen-iron-pnictogen trilayer building block in iron-based superconductivity.

Authors:
 [1];  [2];  [3];  [3];  [4]; ORCiD logo [5]; ORCiD logo [5];  [5]; ORCiD logo [5];  [6];  [7];  [7];  [8];  [3];  [2];  [3];  [3];  [9]
  1. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity; Chinese Academy of Sciences (CAS), Shanghai (China). Shanghai Inst. of Microsystem and Information Technology
  2. Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed Matter Physics and Inst. of Physics
  3. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity
  4. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity; Boston College, Chestnut Hill, MA (United States). Dept. of Physics
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  6. Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics & Astronomy
  7. Rice Univ., Houston, TX (United States). Dept. of Physics and Astronomy
  8. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity; Univ. of Texas at Dallas, Richardson, TX (United States). Dept. of Physics
  9. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity; Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed Matter Physics and Inst. of Physics; Chinese Academy of Sciences (CAS), Beijing (China). School of Physics; Chinese Academy of Sciences (CAS), Beijing (China). CAS Center for Excellence in Topological Quantum Computation; Songshang Lake Material Lab., Dongguan (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1561639
Alternate Identifier(s):
OSTI ID: 1509926
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 99; Journal Issue: 13; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Li, Ang, Yin, Jia-Xin, Wang, Jihui, Wu, Zheng, Ma, Jihua, Sefat, Athena Safa, Sales, Brian C., Mandrus, David, McGuire, Michael A., Jin, Rongying, Zhang, Chenglin, Dai, Pengcheng, Lv, Bing, Chu, Ching-Wu, Liang, Xuejin, Hor, P, Ting, C, and Pan, Shuheng. Surface terminations and layer-resolved tunneling spectroscopy of the 122 iron pnictide superconductors. United States: N. p., 2019. Web. doi:10.1103/physrevb.99.134520.
Li, Ang, Yin, Jia-Xin, Wang, Jihui, Wu, Zheng, Ma, Jihua, Sefat, Athena Safa, Sales, Brian C., Mandrus, David, McGuire, Michael A., Jin, Rongying, Zhang, Chenglin, Dai, Pengcheng, Lv, Bing, Chu, Ching-Wu, Liang, Xuejin, Hor, P, Ting, C, & Pan, Shuheng. Surface terminations and layer-resolved tunneling spectroscopy of the 122 iron pnictide superconductors. United States. doi:10.1103/physrevb.99.134520.
Li, Ang, Yin, Jia-Xin, Wang, Jihui, Wu, Zheng, Ma, Jihua, Sefat, Athena Safa, Sales, Brian C., Mandrus, David, McGuire, Michael A., Jin, Rongying, Zhang, Chenglin, Dai, Pengcheng, Lv, Bing, Chu, Ching-Wu, Liang, Xuejin, Hor, P, Ting, C, and Pan, Shuheng. Tue . "Surface terminations and layer-resolved tunneling spectroscopy of the 122 iron pnictide superconductors". United States. doi:10.1103/physrevb.99.134520.
@article{osti_1561639,
title = {Surface terminations and layer-resolved tunneling spectroscopy of the 122 iron pnictide superconductors},
author = {Li, Ang and Yin, Jia-Xin and Wang, Jihui and Wu, Zheng and Ma, Jihua and Sefat, Athena Safa and Sales, Brian C. and Mandrus, David and McGuire, Michael A. and Jin, Rongying and Zhang, Chenglin and Dai, Pengcheng and Lv, Bing and Chu, Ching-Wu and Liang, Xuejin and Hor, P and Ting, C and Pan, Shuheng},
abstractNote = {The surface terminations of 122-type alkaline earth metal iron pnictides AEFe2As2(AE=Ca,Ba) are investigated with scanning tunneling microscopy/spectroscopy. Cleaving these crystals at a cryogenic temperature yields a large majority of terminations with an atomically resolved (√2 × √2)R45 or 1 × 2 lattice, as well as a very rare termination of 1 × 1 lattice symmetry. By assessing the lattice registration and selective chemical marking, we identify these terminations as (√2 × √2)R45-reconstructed AE, 1 × 2-reconstructed As, and (√2 × √2)R45-reconstructed Fe surface layers, respectively. Layer-resolved tunneling spectroscopy on these terminating surfaces reveals a well-defined superconducting energy gap on the As terminations, while the gap features become weaker on the AE terminations and absent on the Fe terminations. The superconducting gap is hardly affected locally by the As or AE surface reconstructions. The definitive identification of the surface terminations and the associated spectroscopic signatures shed light on the necessary roles of As and the pnictogen-iron-pnictogen trilayer building block in iron-based superconductivity.},
doi = {10.1103/physrevb.99.134520},
journal = {Physical Review B},
issn = {2469-9950},
number = 13,
volume = 99,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on April 30, 2020
Publisher's Version of Record

Save / Share:

Works referenced in this record:

Experimental Investigation of the Electronic Structure of Ca 0.83 La 0.17 Fe 2 As 2
journal, January 2013


2 × 2 structure and charge inhomogeneity at the surface of superconducting BaFe 2 x Co x As 2 ( x = 0 0.32 )
journal, March 2010


Impurity-induced states in conventional and unconventional superconductors
journal, May 2006


Dopant clustering, electronic inhomogeneity, and vortex pinning in iron-based superconductors
journal, June 2013


Neutron Scattering Studies of spin excitations in hole-doped Ba0.67K0.33Fe2As2 superconductor
journal, October 2011

  • Zhang, Chenglin; Wang, Meng; Luo, Huiqian
  • Scientific Reports, Vol. 1, Issue 1
  • DOI: 10.1038/srep00115

Spin-density-wave anomaly at 140 K in the ternary iron arsenide BaFe 2 As 2
journal, July 2008


Surface Geometric and Electronic Structures of BaFe 2 As 2 ( 001 )
journal, August 2009


Scanning Tunneling Spectroscopy and Vortex Imaging in the Iron Pnictide Superconductor BaFe 1.8 Co 0.2 As 2
journal, March 2009


Observation of ordered vortices with Andreev bound states in Ba0.6K0.4Fe2As2
journal, February 2011

  • Shan, Lei; Wang, Yong-Lei; Shen, Bing
  • Nature Physics, Vol. 7, Issue 4
  • DOI: 10.1038/nphys1908

Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors
journal, November 2011


Surface Adatom Conductance Filtering in Scanning Tunneling Spectroscopy of Co-doped BaFe 2 As 2 Iron Pnictide Superconductors
journal, September 2012


Nanoscale superconducting-gap variations and lack of phase separation in optimally doped BaFe 1.86 Co 0.14 As 2
journal, June 2009


Role of Antiferromagnetic Ordering in the ( 1 × 2 ) Surface Reconstruction of Ca ( Fe 1 x Co x ) 2 As 2
journal, February 2014


Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides
journal, September 2011

  • Yin, Z. P.; Haule, K.; Kotliar, G.
  • Nature Materials, Vol. 10, Issue 12
  • DOI: 10.1038/nmat3120

Iron-Based Layered Superconductor La[O 1- x F x ]FeAs ( x = 0.05−0.12) with T c = 26 K
journal, March 2008

  • Kamihara, Yoichi; Watanabe, Takumi; Hirano, Masahiro
  • Journal of the American Chemical Society, Vol. 130, Issue 11
  • DOI: 10.1021/ja800073m

Effect of Pnictogen Height on Spin Waves in Iron Pnictides
journal, May 2014


Observation of a robust zero-energy bound state in iron-based superconductor Fe(Te,Se)
journal, June 2015

  • Yin, J-X.; Wu, Zheng; Wang, J-H.
  • Nature Physics, Vol. 11, Issue 7
  • DOI: 10.1038/nphys3371

Unconventional pairing originating from disconnected Fermi surfaces in the iron-based superconductor
journal, February 2009


Cleavage surfaces of the BaFe 2 x Co x As 2 and Fe y Se 1 x Te x superconductors: A combined STM plus LEED study
journal, October 2009


Unusual superconducting state at 49 K in electron-doped CaFe2As2 at ambient pressure
journal, September 2011

  • Lv, B.; Deng, L.; Gooch, M.
  • Proceedings of the National Academy of Sciences, Vol. 108, Issue 38
  • DOI: 10.1073/pnas.1112150108

Coupled structural and magnetic antiphase domain walls on BaFe 2 As 2
journal, August 2012


Surface Structure and Superconductivity in Ba(Fe 0.93 Co 0.07 ) 2 As 2 Probed by Scanning Tunneling Microscopy/Spectroscopy
journal, January 2011

  • Nishizaki, Terukazu; Nakajima, Yasuyuki; Tamegai, Tsuyoshi
  • Journal of the Physical Society of Japan, Vol. 80, Issue 1
  • DOI: 10.1143/JPSJ.80.014710

Superconductivity in iron compounds
journal, December 2011


Nanoscale surface element identification and dopant homogeneity in the high- T c superconductor Pr x Ca 1 x Fe 2 As 2
journal, May 2013


Superconductivity at 22 K in Co-Doped BaFe 2 As 2 Crystals
journal, September 2008


Close relationship between superconductivity and the bosonic mode in Ba0.6K0.4Fe2As2 and Na(Fe0.975Co0.025)As
journal, November 2012

  • Wang, Zhenyu; Yang, Huan; Fang, Delong
  • Nature Physics, Vol. 9, Issue 1
  • DOI: 10.1038/nphys2478

Surface structures of ternary iron arsenides A Fe 2 As 2 ( A = Ba , Sr, or Ca)
journal, May 2010


Nematic Electronic Structure in the “Parent” State of the Iron-Based Superconductor Ca(Fe 1– x Co x ) 2 As 2
journal, January 2010


Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet
journal, September 2018


The puzzle of high temperature superconductivity in layered iron pnictides and chalcogenides
journal, October 2010