Title page for ETD etd-03172005-000448


Type of Document Master's Thesis
Author David, Priya
Author's Email Address pdavid3@lsu.edu
URN etd-03172005-000448
Title Synthesis and Characterization of Cobalt-Platinum Thin Films
Degree Master of Science in Mechanical Engineering (M.S.M.E.)
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
E.I.Meletis Committee Chair
Dorel Moldovan Committee Member
M.A.Wahab Committee Member
Keywords
  • meletis
  • anisotropy
  • annealing
  • coercivity
  • priya
Date of Defense 2004-12-14
Availability unrestricted
Abstract
Co-based alloy thin films have attracted a lot of interest, due to their excellent magnetic properties, that is essential in the field of magnetic recording media. Alloying Co with metals like Pt changes some of its intrinsic magnetic properties such as increasing the magnetocrystalline anisotropy constants of the alloy. Co-Pt thin films and multilayers are more suitable for ultra high-density magnetic recording media because they have high-magnetic anisotropy, chemical stability, excellent coercivity and resistance to corrosion.

In the present study, Co-Pt alloy and Pt/Co multilayered films were deposited on Si substrate using dual electron beam co-evaporation. The Co-Pt alloy thin films are vacuum-sealed and annealed for 2 hours at 300C and 400C to study the annealing effects on structural and magnetic properties. All the films were characterized using scanning and transmission electron microscopy, electron microprobe, and profilometry. In Co-Pt alloy films, Co and Pt were present in the atomic ratio of 3:1. A mixture of hexagonal close packed and face centered cubic structure Co3Pt was present in both as-deposited and annealed films. The magnetic measurements were conducted at 300K and 10K in both perpendicular and parallel orientations in physical property measurement system (PPMS) and magnetic property measurement system (MPMS).

The results from analytical and characterization techniques showed the addition of Pt to Co increased the coercivity of the films. Annealing enhanced the grain size and coercivity of the as-deposited Co3Pt film. However, the presence of ε-Co decreased the coercivity of the Co-Pt film annealed at 400C.

Asymmetry in the hysterisis loops was observed for all films at 10K. The antiferromagnetic CoO and ferromagnetic Co and Co3Pt undergo exchange coupling at the interface and give rise to exchange anisotropy leading to the shift in the hysterisis loop. This property of the Co-Pt alloy thin film system may find its application in the magnetic sensor systems, like spin valve and magnetoresistance devices.

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