Magnetic and Magnetotransport Properties of (Co,Fe)S2 thin films

Nikolaos Moutis 1Ioannis Panagiotopoulos 2Michael Ziese 3Thanassis Speliotis 1

1. Institute of Materials Science "Demokritos", 15 310 Ag.Paraskevi, Athens 153 10, Greece
2. Department of Materials Science and technology, University of Ioannina, Ioannina 45110, Greece
3. Universit├Ąt Leipzig, Linnestr. 3, Leipzig 04103, Germany

Abstract

Recently Co1-xFexS2 has been proposed as a tunable source of highly spin-polarized electrons, based on the fact that the Fermi level may be fine-tuned by solid solution alloying with the isostructural diamagnetic semiconductor FeS2 having the pyrite structure. Anisotropic magnetoresistance measurements have been used as a probe of the sign of carrier polarization.

In this study we report on the preparation, magnetic and magnetotransport properties, of (Co,Fe)S2 thin films. The films have been prepared by thermal-sulfuration of Co1-xFex films in a sulfur atmosphere at 5000C, at a sulfur pressure of 1 atm for 12 hrs. Co50Fe50 films prepared by Pulsed Laser Deposition (PLD) as well as Magnetron Sputtered Co30Fe70 films have been used. Proper adjustment of heat treatment conditions is crucial in order to achieve the correct sulfur stoichoiometry throughout the film. Thicker films show a cusp in the magnetization versus temperature curves around 100K which indicates an inhomogeneous nature.

The resistivity decreases monotonously as a function of temperature and shows a plateau at the Curie temperature. In the MR curves a small (2%) low field extrinsic contribution is observed at 5K which decreases rapidly with temperature and disappears well below the Curie temperature of 135K. This extrinsic MR is increased (4%) for thinner films. Above the Curie temperature a quadratic MR term dominates. The coercivity decreases linearly with temperature. The Hall effect measurements show a substantial Anomalous Hall Effect (AHE) contribution that is superimposed at the ordinary Hall effect and disappears at the TC.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium K, by Ioannis Panagiotopoulos
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 22:06
Revised:   2009-06-07 00:44