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Title: Scanning-probe-microscopy studies of superlattice structures and density-wave structures in 2H-NbSe[sub 2], 2H-TaSe[sub 2], and 2H-TaS[sub 2] induced by Fe doping

Abstract

The intercalation of Fe into the van der Waals gap in the 2H phase transition-metal dichalcogenides NbSe[sub 2], TaSe[sub 2], and TaS[sub 2] produces many interesting electronic, magnetic, and structural effects. The scanning tunneling microscope (STM) and atomic force microscope (AFM) prove to be very sensitive to these changes and we report a wide range of results as a function of Fe concentration. All three materials support similar 3[bold a][sub 0][times]3[bold a][sub 0] charge-density-wave (CDW) structures in the pure state at low temperatures. At low concentrations of Fe the CDW superlattice is still strong at 4.2 K and persists to high concentrations of Fe. At high concentrations, the Fe becomes ordered in the octahedral holes in the van der Waals gaps, and superlattices of the form 2[bold a][sub 0][times]2[bold a][sub 0] and [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] are observed. These can be detected at both 300 and 4.2 K. STM spectroscopy at 4.2 K shows that in 2H-Fe[sub [ital x]]NbSe[sub 2] and 2H-Fe[sub [ital x]]TaSe[sub 2] the energy gap in the electronic spectrum is initially reduced, but stabilizes at higher Fe concentrations and remains well defined for the ordered 2[bold a][sub 0][times]2[bold a][sub 0] phase. A transitionmore » from a CDW to a mixed CDW and spin-density-wave state is indicated, since these high Fe concentration phases are antiferromagnetic. In 2H-Fe[sub [ital x]]TaS[sub 2] both 2[bold a][sub 0][times]2[bold a][sub 0] and [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] superlattices are observed. The 2[bold a][sub 0][times]2[bold a][sub 0] regions show a large energy gap, while the [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] do not. The latter phase is ferromagnetic and would not be expected to exhibit a gap.« less

Authors:
; ; ; ;  [1]
  1. Physics Department, University of Virginia, Charlottesville, Virginia 22901 (United States)
Publication Date:
OSTI Identifier:
5725977
DOE Contract Number:  
FG05-84ER45072
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter; (United States)
Additional Journal Information:
Journal Volume: 48:19; Journal ID: ISSN 0163-1829
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; NIOBIUM SELENIDES; CHARGE DENSITY; TANTALUM SELENIDES; TANTALUM SULFIDES; CRYSTAL STRUCTURE; ELECTRON SPECTRA; IRON ADDITIONS; SUPERLATTICES; ALLOYS; CHALCOGENIDES; IRON ALLOYS; NIOBIUM COMPOUNDS; REFRACTORY METAL COMPOUNDS; SELENIDES; SELENIUM COMPOUNDS; SPECTRA; SULFIDES; SULFUR COMPOUNDS; TANTALUM COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; 360204* - Ceramics, Cermets, & Refractories- Physical Properties

Citation Formats

Dai, Z, Xue, Q, Gong, Y, Slough, C G, and Coleman, R V. Scanning-probe-microscopy studies of superlattice structures and density-wave structures in 2H-NbSe[sub 2], 2H-TaSe[sub 2], and 2H-TaS[sub 2] induced by Fe doping. United States: N. p., 1993. Web. doi:10.1103/PhysRevB.48.14543.
Dai, Z, Xue, Q, Gong, Y, Slough, C G, & Coleman, R V. Scanning-probe-microscopy studies of superlattice structures and density-wave structures in 2H-NbSe[sub 2], 2H-TaSe[sub 2], and 2H-TaS[sub 2] induced by Fe doping. United States. https://doi.org/10.1103/PhysRevB.48.14543
Dai, Z, Xue, Q, Gong, Y, Slough, C G, and Coleman, R V. 1993. "Scanning-probe-microscopy studies of superlattice structures and density-wave structures in 2H-NbSe[sub 2], 2H-TaSe[sub 2], and 2H-TaS[sub 2] induced by Fe doping". United States. https://doi.org/10.1103/PhysRevB.48.14543.
@article{osti_5725977,
title = {Scanning-probe-microscopy studies of superlattice structures and density-wave structures in 2H-NbSe[sub 2], 2H-TaSe[sub 2], and 2H-TaS[sub 2] induced by Fe doping},
author = {Dai, Z and Xue, Q and Gong, Y and Slough, C G and Coleman, R V},
abstractNote = {The intercalation of Fe into the van der Waals gap in the 2H phase transition-metal dichalcogenides NbSe[sub 2], TaSe[sub 2], and TaS[sub 2] produces many interesting electronic, magnetic, and structural effects. The scanning tunneling microscope (STM) and atomic force microscope (AFM) prove to be very sensitive to these changes and we report a wide range of results as a function of Fe concentration. All three materials support similar 3[bold a][sub 0][times]3[bold a][sub 0] charge-density-wave (CDW) structures in the pure state at low temperatures. At low concentrations of Fe the CDW superlattice is still strong at 4.2 K and persists to high concentrations of Fe. At high concentrations, the Fe becomes ordered in the octahedral holes in the van der Waals gaps, and superlattices of the form 2[bold a][sub 0][times]2[bold a][sub 0] and [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] are observed. These can be detected at both 300 and 4.2 K. STM spectroscopy at 4.2 K shows that in 2H-Fe[sub [ital x]]NbSe[sub 2] and 2H-Fe[sub [ital x]]TaSe[sub 2] the energy gap in the electronic spectrum is initially reduced, but stabilizes at higher Fe concentrations and remains well defined for the ordered 2[bold a][sub 0][times]2[bold a][sub 0] phase. A transition from a CDW to a mixed CDW and spin-density-wave state is indicated, since these high Fe concentration phases are antiferromagnetic. In 2H-Fe[sub [ital x]]TaS[sub 2] both 2[bold a][sub 0][times]2[bold a][sub 0] and [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] superlattices are observed. The 2[bold a][sub 0][times]2[bold a][sub 0] regions show a large energy gap, while the [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] do not. The latter phase is ferromagnetic and would not be expected to exhibit a gap.},
doi = {10.1103/PhysRevB.48.14543},
url = {https://www.osti.gov/biblio/5725977}, journal = {Physical Review, B: Condensed Matter; (United States)},
issn = {0163-1829},
number = ,
volume = 48:19,
place = {United States},
year = {Mon Nov 15 00:00:00 EST 1993},
month = {Mon Nov 15 00:00:00 EST 1993}
}