Observation Of Strain Wave In The Nematic Phase Of The Iron Pnictide Ba(Fe1-xCux)2As2 Using Dark-Field X-Ray Microscopy

MPSD Seminar

  • Date: Oct 7, 2024
  • Time: 01:00 PM - 02:00 PM (Local Time Germany)
  • Speaker: Kaan Alp Yay
  • Stanford University
  • Location: MPSD Bldg. 900
  • Room: Seminar Room EG.136

Kaan Alp Yay1,2, Elliot Kisiel4,5, Matthew J. Krogstad4, Doga Gursoy4, Stephan O. Hruszkewycz4, Zahir Islam4, Ian R. Fisher1,3

1Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305
2Department of Physics, Stanford University, Stanford, CA 94305
3Department of Applied Physics, Stanford University, Stanford, CA 94305
4Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439
5Department of Physics, University of California San Diego, La Jolla, CA 92093

To gain a better understanding of the nematic phase in iron pnictides, we study underdoped Ba(Fe1-xCux)2As2 (Cu-Ba122) using dark-field X-ray microscopy (DFXM). DFXM is a novel technique which enables one to image the real-space distribution of a selected diffraction peak emanating from a domain within the bulk of a sample. Cu-Ba122 undergoes a tetragonal-to-orthorhombic structural phase transition at low temperature due to electronic nematicity, at which point orthorhombic twin domains form along the ab-plane. By imaging a single domain, we observed (1) micron-scale periodic spatial modulations of diffraction intensity and strain within a domain, and (2) an increase in the amplitude and period of the spatial modulations as temperature is lowered.

These observations demonstrate the existence of a mesoscopic strain wave within the orthorhombic phase of iron pnictides that has so far been undetected in traditional X-ray diffraction due to its long wavelength. Our results also establish DFXM as a powerful new tool to probe the mesoscopic behavior of strongly-correlated quantum materials.

Work at Stanford was supported by the Department of Energy, Office of Basic Energy Sciences, under contract DE-AC02-76SF00515. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

If you would like to meet with Kaan during his visit, please contact Susan LaMoreaux.


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