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Chemical Vapor Deposition and Correlated Characterizations of Nanostructured Metal Chalcogenides and Oxides.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Chemical Vapor Deposition and Correlated Characterizations of Nanostructured Metal Chalcogenides and Oxides./
Author:	Coughlin, Amanda.
Description:	1 online resource (161 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Physics. -
Online resource:	click for full text (PQDT)
ISBN:	9798380375603

Chemical Vapor Deposition and Correlated Characterizations of Nanostructured Metal Chalcogenides and Oxides.
Coughlin, Amanda.

Chemical Vapor Deposition and Correlated Characterizations of Nanostructured Metal Chalcogenides and Oxides. - 1 online resource (161 pages)

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

Thesis (Ph.D.)--Indiana University, 2023.

Includes bibliographical references

The discovery of van der Waals (vdW) magnets has created unprecedented opportunities to explore two-dimensional (2D) magnetism for innovative spintronics applications. Among them, the self-intercalated chromium tellurides (Cr1+δTe2) have emerged as promising candidates for spintronics devices and have attracted growing interests due to their high-temperature perpendicular ferromagnetism, topologically nontrivial spin textures, and large anomalous Hall effect. In this work, we synthesize high-quality nanoplates of various phases of Cr1+δTe2 nanoplates via chemical vapor deposition. Magnetization measurements reveal a ferromagnetic ordering with enhanced perpendicular magnetic anisotropy and an easy axis along the c-axis on Cr2Te3 nanoplates. Additionally, a kink-like feature near zero magnetic field was observed which can be explained by a near degeneracy of magnetic orderings, as suggested by the first-principles density functional theory calculations (DFT). The existence of vdW 'superstructures' are also demonstrated in individual Cr1+δTe2 nanoplates which exhibit magnetic behaviors distinct from bulk chromium tellurides. The exact Cr-intercalation was determined through detailed selected area electron diffraction transmission electron microscopy (SAED-TEM) studies along three zone axes and exhaustive simulations of SAED patterns. Additionally, we demonstrate a rapid oxidation of Cr1+δTe2 within only minutes of exposure to ambient conditions, as evidenced by dramatic changes occur in the Raman and X-ray photoelectron spectroscopy spectra of nanoplates at room temperature. Time-dependent magnetization measurements and TEM studies suggested the rapid oxidation is not self-limited and has distinct processes on the surfaces and edges. DFT calculations confirmed the spontaneous oxygen adsorption on the surface and the thermodynamically favorable oxidation process. This work highlights the necessity of surface protection for practical applications of advanced spintronic devices. Lastly, we enhance electron correlation in a prototypical topological metal, namely iridium dioxide, via doping with vanadium, as evidenced by a dramatic decrease in Raman intensity without notable peak broadening with increasing vanadium dopants, and transport studies where the electrical resistivity is greatly increased and follows an unusual √\uD835\uDC47 dependence.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380375603Subjects--Topical Terms:

564049
Physics.
Subjects--Index Terms:

MagnetsIndex Terms--Genre/Form:

554714
Electronic books.

Chemical Vapor Deposition and Correlated Characterizations of Nanostructured Metal Chalcogenides and Oxides.
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520 $a The discovery of van der Waals (vdW) magnets has created unprecedented opportunities to explore two-dimensional (2D) magnetism for innovative spintronics applications. Among them, the self-intercalated chromium tellurides (Cr1+δTe2) have emerged as promising candidates for spintronics devices and have attracted growing interests due to their high-temperature perpendicular ferromagnetism, topologically nontrivial spin textures, and large anomalous Hall effect. In this work, we synthesize high-quality nanoplates of various phases of Cr1+δTe2 nanoplates via chemical vapor deposition. Magnetization measurements reveal a ferromagnetic ordering with enhanced perpendicular magnetic anisotropy and an easy axis along the c-axis on Cr2Te3 nanoplates. Additionally, a kink-like feature near zero magnetic field was observed which can be explained by a near degeneracy of magnetic orderings, as suggested by the first-principles density functional theory calculations (DFT). The existence of vdW 'superstructures' are also demonstrated in individual Cr1+δTe2 nanoplates which exhibit magnetic behaviors distinct from bulk chromium tellurides. The exact Cr-intercalation was determined through detailed selected area electron diffraction transmission electron microscopy (SAED-TEM) studies along three zone axes and exhaustive simulations of SAED patterns. Additionally, we demonstrate a rapid oxidation of Cr1+δTe2 within only minutes of exposure to ambient conditions, as evidenced by dramatic changes occur in the Raman and X-ray photoelectron spectroscopy spectra of nanoplates at room temperature. Time-dependent magnetization measurements and TEM studies suggested the rapid oxidation is not self-limited and has distinct processes on the surfaces and edges. DFT calculations confirmed the spontaneous oxygen adsorption on the surface and the thermodynamically favorable oxidation process. This work highlights the necessity of surface protection for practical applications of advanced spintronic devices. Lastly, we enhance electron correlation in a prototypical topological metal, namely iridium dioxide, via doping with vanadium, as evidenced by a dramatic decrease in Raman intensity without notable peak broadening with increasing vanadium dopants, and transport studies where the electrical resistivity is greatly increased and follows an unusual √\uD835\uDC47 dependence.
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