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Negative giant longitudinal magnetoresistance in NiMnSb/InSb: An interface effect
|Spiros Gardelis 1,2, John Androulakis 2, Zacharias Viskadourakis 2, Evie L. Papadopoulou 2, Sanjay Rai 3, Gyanendra S. Lodha 3, Sindhunil B. Roy 3, John Giapintzakis 2,4
1. IMEL, NCSR Demokritos, Aghia Paraskevi, Athens 15310, Greece
We report on the electrical and magneto-transport properties of the ohmic contact between polycrystalline NiMnSb thin films grown using pulsed laser deposition (PLD) and n-type degenerate InSb (100) substrates. An unusual negative giant magnetoresistance (n-GMR) effect is found when the external magnetic field is parallel to the in-plane current direction. A similar effect is also observed when Ni films are deposited on InSb substrates. On the other hand, no n-GMR effect is displayed when the deposited film is nonmagnetic. Grazing-incidence x-ray reflectometry (XRR) shows the formation of a low-density NiMnSb layer at the interface. The presence of such a layer coincides with the appearance of the n-GMR. We argue that the n-GMR effect is due to magnetic precipitates formed at the interface during the growth of the magnetic films. We propose that these precipitates align their magnetic moments in the direction of the external magnetic field and thus, the spin dependent scattering of the electrons is reduced. The effect of these precipitates on the magnetoresistance depends on the thermal processing of the system.
This work was supported by the EU contract FENIKS: G5RD-CT-2001-00535.
Presentation: Oral at E-MRS Fall Meeting 2006, Symposium E, by Spiros Gardelis
See On-line Journal of E-MRS Fall Meeting 2006
Submitted: 2006-05-12 14:51 Revised: 2009-06-07 00:44