Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors

H Pfau; S D Chen; M Yi; M Hashimoto; C R Rotundu; J C Palmstrom; T Chen; P-C Dai; J Straquadine; A Hristov; R J Birgeneau; I R Fisher; D Lu; Z-X Shen

doi:10.1103/PhysRevLett.123.066402

Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors

Phys Rev Lett. 2019 Aug 9;123(6):066402. doi: 10.1103/PhysRevLett.123.066402.

Authors

H Pfau^{1

2}, S D Chen³, M Yi^{4

5}, M Hashimoto⁶, C R Rotundu¹, J C Palmstrom^{1

3}, T Chen⁵, P-C Dai⁵, J Straquadine³, A Hristov³, R J Birgeneau⁴, I R Fisher^{1

3}, D Lu⁶, Z-X Shen^{1

3

7}

Affiliations

¹ Stanford Institute of Materials and Energy Sience, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
² Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
³ Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, 94305 California, USA.
⁴ Department of Physics, University of California, Berkeley, 94720 California, USA.
⁵ Department of Physics and Astronomy, Rice University, Houston, 77005 Texas, USA.
⁶ Stanford Synchrotron Radiation Lightsource, SLAC National Acelerator Laboratory, Menlo Park, 94025 California, USA.
⁷ Department of Physics, Stanford University, Stanford, 94305 California, USA.

PMID: 31491189
DOI: 10.1103/PhysRevLett.123.066402

Abstract

The momentum dependence of the nematic order parameter is an important ingredient in the microscopic description of iron-based high-temperature superconductors. While recent reports on FeSe indicate that the nematic order parameter changes sign between electron and hole bands, detailed knowledge is still missing for other compounds. Combining angle-resolved photoemission spectroscopy with uniaxial strain tuning, we measure the nematic band splitting in both FeSe and BaFe_{2}As_{2} without interference from either twinning or magnetic order. We find that the nematic order parameter exhibits the same momentum dependence in both compounds with a sign change between the Brillouin center and the corner. This suggests that the same microscopic mechanism drives the nematic order in spite of the very different phase diagrams.