Interface effects in ultra-thin films: Magnetic and chemical properties

Persistent Link:
http://hdl.handle.net/10150/279832
Title:
Interface effects in ultra-thin films: Magnetic and chemical properties
Author:
Park, Sungkyun
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
When the thickness of a magnetic layer is comparable to (or smaller than) the electron mean free path, the interface between magnetic and non-magnetic layers becomes very important factor to determine magnetic properties of the ultra-thin films. The quality of interface can enhance (or reduce) the desired properties. Several interesting physical phenomena were studied using these interface effects. The magnetic anisotropy of ultra-thin Co films is studied as function of non-magnetic underlayer thickness and non-magnetic overlayer materials using ex situ Brillouin light scattering (BLS). I observed that perpendicular magnetic anisotropy (PMA) increases with underlayer thickness and saturates after 5 ML. This saturation can be understood as a relaxation of the in-plane lattice parameter of Au(111) on top of Cu(111) to its bulk value. For the overlayer study, Cu, Al, and Au are used. An Au overlayer gives the largest PMA due to the largest in-plane lattice mismatch between Co and Au. An unusual effect was found by adding an additional layer on top of the Au overlayer. An additional Al capping layer on top of the Au overlayer reduces the PMA significantly. The possible explanation is that the misfit strain at the interface between the Al and the Au can be propagated through the Au layer to affect the magnetic properties of Co even though the in-plane lattice mismatch is less than 1%. Another interesting problem in interface interdiffusion and thermal stability in magnetic tunnel junction (MTJ) structures is studied using X-ray photoelectron spectroscopy (XPS). Since XPS is a very chemically sensitive technique, it allows us to monitor interface interdiffusion of the MTJ structures as-deposited and during post-deposition processing. For the plasma-oxidized samples, Fe only participates in the oxidation reduction process. In contrast to plasma-oxidized samples, there were no noticeable chemical shifts as-deposited and during post-deposition processing in air-oxidized samples. However, peak intensity variations were observed due to interface interdiffusion.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Physics, Electricity and Magnetism.; Physics, Condensed Matter.; Physics, Optics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Physics
Degree Grantor:
University of Arizona
Advisor:
Falco, Charles M.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleInterface effects in ultra-thin films: Magnetic and chemical propertiesen_US
dc.creatorPark, Sungkyunen_US
dc.contributor.authorPark, Sungkyunen_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractWhen the thickness of a magnetic layer is comparable to (or smaller than) the electron mean free path, the interface between magnetic and non-magnetic layers becomes very important factor to determine magnetic properties of the ultra-thin films. The quality of interface can enhance (or reduce) the desired properties. Several interesting physical phenomena were studied using these interface effects. The magnetic anisotropy of ultra-thin Co films is studied as function of non-magnetic underlayer thickness and non-magnetic overlayer materials using ex situ Brillouin light scattering (BLS). I observed that perpendicular magnetic anisotropy (PMA) increases with underlayer thickness and saturates after 5 ML. This saturation can be understood as a relaxation of the in-plane lattice parameter of Au(111) on top of Cu(111) to its bulk value. For the overlayer study, Cu, Al, and Au are used. An Au overlayer gives the largest PMA due to the largest in-plane lattice mismatch between Co and Au. An unusual effect was found by adding an additional layer on top of the Au overlayer. An additional Al capping layer on top of the Au overlayer reduces the PMA significantly. The possible explanation is that the misfit strain at the interface between the Al and the Au can be propagated through the Au layer to affect the magnetic properties of Co even though the in-plane lattice mismatch is less than 1%. Another interesting problem in interface interdiffusion and thermal stability in magnetic tunnel junction (MTJ) structures is studied using X-ray photoelectron spectroscopy (XPS). Since XPS is a very chemically sensitive technique, it allows us to monitor interface interdiffusion of the MTJ structures as-deposited and during post-deposition processing. For the plasma-oxidized samples, Fe only participates in the oxidation reduction process. In contrast to plasma-oxidized samples, there were no noticeable chemical shifts as-deposited and during post-deposition processing in air-oxidized samples. However, peak intensity variations were observed due to interface interdiffusion.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectPhysics, Electricity and Magnetism.en_US
dc.subjectPhysics, Condensed Matter.en_US
dc.subjectPhysics, Optics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorFalco, Charles M.en_US
dc.identifier.proquest3026563en_US
dc.identifier.bibrecord.b42177510en_US
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