7-11 July 2014
Africa/Johannesburg timezone
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Electrical properties of Cr100-x Cox alloy thin films on oriented MgO (100)

Presented by Dr. M KADAM on 8 Jul 2014 from 17:10 to 19:00
Type: Poster Presentation
Session: Poster1
Track: Track A - Division for Physics of Condensed Matter and Materials
Board #: A.293

Abstract

The magnetic phase diagrams of Cr with group-8 magnetic transition metals Co and Fe exhibits a triple point, where the incommensurate (I) spin density wave (SDW), commensurate (C) SDW and paramagnetic (P) phases converge [1]. Cr-Co alloys has shown considerable promise in practical applications because of its Invar-like properties [2], as well as the fact that Cr/Co multi-layered systems show enhancement of the SDW due to the exchange interaction between the Co moments and the SDW these alloys [3]. This can find application in recording and storage media. Comparison between Cr in bulk and thin film forms revealed dimensionality plays an important role in modifying the SDW structure [4] and this study extends these investigations to include Cr-Co. Epitaxial Cr<sub>100-<i>x</i></sub>Co<sub><i>x</i></sub> thin films of thickness (<i>t</i>) 200nm, with 0 < <i>x</i> < 8, were prepared on MgO(100) substrates using DC magnetron co-sputtering techniques. The epitaxial nature of these monolayers was confirmed using XRD analyses. The resistivity (<i>ρ</i>) for these samples was determined in the temperature range 2K < <i>T</i> < 395K and the temperature associated with the minimum in the d<i>ρ</i>/d<i>T</i> versus <i>T</i> curves were used to determine the Néel transition temperatures (<i>T</i><sub>N</sub>) for the individual samples. The <i>T</i><sub>N</sub> versus <i>x</i> plot for this sample series shows that <i>T</i><sub>N</sub> decreases up to 2at.% Co and then increases, reaching a maximum at approximately 6at.% Co. Hall coefficients (<i>R</i><sub>H</sub> ) for the films with <i>x</i> = 1 and 4 were determined on cooling from 300K down to 2K, in a constant magnetic field of 5 T. Interestingly, the <i>R</i><sub>H</sub> versus <i>T</i> plots appears to reveal a spin-flip transition at about 100K for 1at.% Co thin film, while it is absent for 4at.% Co sample. The present results will shed light on the effect of dimensionality on the electrical properties of the Cr-Co alloys. [1] Fawcett E <i>et al</i>. 1994 <i>Rev. Mod. Phys.</i> <b> 66 </b> 25 [2] K. Fukamichi <i>et al</i>. 1976 <i>Trans. Jpn. Inst. Metall.</i>. <b> 17 </b> 125 [3] Ge S <i>et al</i>. 1988 <i>J. Appl. Phys</i> <b> 63 </b>(8) 4297 [4] Zabel H 1999 <i>J.Phys. Condens. Matter</i> <b> 11 </b> 9303

Award

No

Level

-

Supervisor

CJ Sheppard cjsheppard@uj.ac.za UJ

Paper

Yes

Place

Room: D Ring ground level


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