Surface and Bulk Charge Density Wave Structure in 1 T-TaS2

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Science  17 Jul 1992:
Vol. 257, Issue 5068, pp. 362-364
DOI: 10.1126/science.257.5068.362


Incommensurate charge density waves (CDWs) in some materials form domains within which the CDWs may be commensurate. However, two questions have remained controversial: What is the geometrical structure of these domains, and are they or are they not identical on the surface and in the bulk? To address these issues in the triclinic (T) phase of tantalum disuffide (1T-TaS2) the CDW domain structure has been accurately determined for both the crystal surface and the crystal bulk. By analyzing the bulk CDW wave vectors and associated satellites by x-ray diffraction, it is found that the bulk contains three dimensionally ordered striped domains that have previously been misidentified. Scanning tunneling microscope images show that the striped domain configuration propagates unaltered to the crystal surface, and their Fourier transforms yield the same satellite positions as the x-rays. These observations demonstrate that the surface and bulk CDW domain structures in 1T-TaS2 are identical.