Ab Rahman, Nur Alifah Binti (2019) Ferromagnetic MnSb growth on graphene. PhD thesis, University of Warwick.

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Abstract

Integration of ferromagnetic and 2-dimensional material is of interest for potential spin transport applications. Most research materials support the importance of graphene application in many sectors and industries due to its electronic, thermal and chemical properties and potential of being magnetised. This study aimed at fabricating graphene on polycrystalline copper plate with chemical vapour deposition (CVD) and then used it as a substrate to grow epitaxial layers of MnSb by molecular beam epitaxy (MBE). It has been motivated by the transfer of sample in MBE which needs rigid copper substrate to overcome the foil limitation.

The study involved several experiments with the first being focused on pre-growth substrate preparation, graphene growth on Cu plate and single crystal. Graphene growth on Cu(100) and Cu(410) showed the structural feedback or faceting that happened on foil and plate also appeared on bulk single crystal. Graphene domain formation for Cu plate is a mixture of different grain boundaries of crystallography. Important techniques such as SEM, EBSD, AFM, XPS, Raman spectroscopy, RHEED, LEED, and magnetometry were utilised in this experiment. MnSb was chosen due to its promising ferromagnetic materials and the hope that it will be a cubic MnSb (c-MnSb) which can be manipulated as spintronic materials. The quality of monolayer graphene on Cu plate was confirmed by Raman with 2D/G peak ratio between 2 to 4. It then used as substrate for epitaxial growth MnSb on graphene. Although the ultimate aim is to induce magnetism in the graphene layer, the evidence discussed cannot provide the epitaxial behaviour in total.

The magnetic hysteresis loop was detected with the coercive field (667 ± 5) Oe and (900 ± 20) Oe at 300 K and 10 K respectively. The shallow core XPS region for Mn 3p was fitted carefully and showed a metallic state consistent with MnSb.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QC Physics Q Science > QD Chemistry T Technology > TA Engineering (General). Civil engineering (General) T Technology > TS Manufactures
Library of Congress Subject Headings (LCSH):	Graphene, Ferromagnetism, Spintronics, Chemical vapor deposition, Molecular beam epitaxy, Antimony compounds, Manganese compounds
Official Date:	January 2019
Dates:	Date Event January 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bell, Gavin R. ; Hase, Thomas P. A.
Format of File:	pdf
Extent:	xiv, 142 leaves : illustrations, charts
Language:	eng

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