Fabrication and characterization of perpendicular magnetic anisotropy thin-film CoCrPt grown on a Ti underlayer

CoCrPt has potential applications as a memory storage technology because of its perpendicular magnetic anisotropy (PMA) characteristics. An underlayer can be used to ensure the out-of-plane magnetization required for PMA functionalities. Ti, with a lattice constant of a = 2.95 Å can be used to encourage uniaxial c-axis growth in CoCrPt (lattice constant a ~/= 2.55 Å, dependent on exact composition). In this report, varying thicknesses of Ti (t = 0, 20, 40, 60, 70, 80, 90, 100nm) and CoCrPt (t = 50, 75, 90, 100, 125, 150nm) were sputtered onto naturally oxidized silicon substrates. Using various characterization methods, these films were investigated in order to better understand the system. The exact composition of the CoCrPt films was found to be approximately Co₆₀.₂Cr₁₆.₄Pt₂₃.₄, with a Curie temperature of about 600 °C. The addition of a Ti underlayer resulted in an increase in coercivity to approximately 1250 Oe for t > 60nm. However, switching field distribution and saturation magnetization appear to be independent of underlayer thickness. All samples show evidence of out-of-plane growth and the roughness of the films increases until it also plateaus at about t = 60nm. When CoCrPt thickness is varied on a constant Ti underlayer, the PMA properties of the materials decrease with increasing thickness due to increased disorder and potential relaxation of the lattice in thicker films. The switching field distribution shows a significant increase, implying that a thicker film has a more homogenous distribution of grain sizes. XRD peaks confirm out-of-plane growth and suggest a trend of increasing c lattice constant as the thickness of the film increases.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2015

Author dc:creator

• Kane, Margaret Marie

Advisor dc:contributor.advisor

• Caroline Ross.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/98555

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/98555