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# Yen-Ru Lee <junolee@uiuc.edu>
# requesting 7 days, at minimum=5 days
# beamline 33ID, Surface reconstruction studies of Fe3O4 films using pulsed laser deposition
# instrument 33ID-D laser
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# top:/home/www/beamtime-requests/req00714.txt
# UNICAT Member Beam Time Request  #714
# created Sun Dec 05 20:47:28 CST 2004
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apsrun:
	2005-01

beamline:
	33ID

collaboration:
	Yes

contact:
	junolee@uiuc.edu

days:
	7

description:
	The magnetite Fe3O4 is the earliest known magnet, and is still an interesting and important material owing to its catalytic, magnetic, semiconducting properties, and widespread applications. The chemical and morphological properties of these films, such as stoichiometry and grain size, can influence both the extrinsic and intrinsic magnetic and electrical properties. For instance, variations in stoichiometry in Fe3O4 will reduce the magnetization through iron vacancies in the B-site magnetic sublattice. Grain size and shape can significantly change the extrinsic properties of a magnetic oxide film. The influence of thickness is a key issue to reveal structural characterization. With increasing thickness the grain size would be enlarged, and to lower values decreasing the thickness, attributed to the interfacial strain effect would show a shift in the Verwey transition temperature, Tv. If the thickness lower than a limit this transition can be completely eliminated. We also believe that for a specific thick film indicating a relaxation for this film. 
In order to better understand and tailor its surface relaxation and reconstruction, thin film of Fe3O4 would be grown by pulsed laser deposition (PLD) on MgO, sapphire and MgAl2O4 substrates. MgO is commonly used as a substrate for the deposition of Fe3O4 due to both materials the O atoms form a fcc structure with 0.3% a small lattice mismatch between them.  This small mismatch allows pseudomorphic growth causing strain during an early stage of growth. And the lattice constant of MgO (a=4.212A) is about half that of Fe3O4(a=8.397A) attributed to the stacking defects in the sublattices. The defects existing atomic location shift between neighboring Fe3O4 islands, which are known as antiphase domain boundaries and have consequences on the magnetic properties and magnrto-transport properties.  
We propose doing an in-situ growth of study of Fe3O4 films grown on MgO or sapphire using PLD to reveal its surface relaxation, reconstruction and possibly kinetics, during the stages of growth using surface x-ray diffraction.

equipment_required:
	

experiment:
	Surface reconstruction studies of Fe3O4 films using pulsed laser deposition

foreign_nationals:
	

hazards:
	Class 4 laser will be used

instrument:
	33ID-D laser

instrument_other:
	

minimumdays:
	5

name:
	Yen-Ru Lee

new_request:
	ON

nonmembers:
	John Z. Tischler

unacceptable_dates:
	March 21-25, 2004
Feb. 8-12, 2004

z34ID_details:
	


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