Identifier

etd-01222013-162013

Degree

Master of Science (MS)

Department

Physics and Astronomy

Document Type

Thesis

Abstract

The Kerr rotation and Kerr ellipticity of thin films can be measured using an AC magneto-optic Kerr effect (AC-MOKE) system. The longitudinal MOKE measurements were taken for a series of Co2MnSixAl1-x thin films with values of x= 0.00, 0.25, 0.50, 0.75, 1.00. The films were fabricated using ultra high vacuum, pulsed laser deposition (PLD) techniques. The PLD targets were made using conventional arc-melting techniques. Using a Jones matrix analysis, it was shown that the Kerr rotation and Kerr ellipticity can be measured separately using two optical setups by taking advantage of a photoelastic modulator and lock-in techniques. Co2MnAl and Co2MnSi are both in a class of materials known as Heusler alloys and are predicted to have a high degree of spin polarization. The crystal structure was confirmed as the L21 using powder x-ray diffraction. The lattice constants were shown to be 5.61Å and 5.77 Å for Co2MnSi andCo2MnAl, respectively. For each film, the DC-MOKE, AC-Kerr rotation, and AC- Kerr ellipticity were measured. The DC-MOKE loops were used to estimate the total Kerr rotation. There was no noticeable trend in the values of the total Kerr rotation as calculated using a technique based on Malus’ law. The Kerr rotation showed a decreasing trend with concentration (x). The sample with x=0.50 was calculated to be the same as the one with x=0.00 value. The Kerr ellipticity also decreased as x was increased. There have been no reports in the literature on direct measurements of the Kerr rotation or ellipticity for Co2MnSixAl1-x for any values of x. The measurements gave values that were comparable to reported calculations and measured values of similar Heusler alloys.

Date

2013

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Stadler, Shane

DOI

10.31390/gradschool_theses.635

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