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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:27 |
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Conference: Bucharest University Faculty of Physics 2001 Meeting
Section: Optics and Spectroscopy
Title:
SOME CONSIDERATION ABOUT THE GMR EFFECT
Authors:
I Mustata, G. Musa, C. Cudalbu, S. Viorel
Affiliation:
i
E-mail
Keywords:
Abstract:
In this article we will present some new obtained data using TVA deposition technology concerning the recent discovered effect: Giant Magnetoresistence (GMR).
There are three kinds of magnetoresistance:
- normal magnetoresistence (MR) which appears in nonmagnetic metals.
- anisotrope magneto-resistence (AMR) which appears in the feromagnetic metals and depends on the direction of the magnetization at the surface
- giant magnetoresistence that is a powerful decrease of the electrical resistance in an applied magnetic field.
The effect is better observed in thin film structures composed by transition 3d metals and noble metals like gold, silver or copper.
In our laboratory we made deposition of thin film in the installation which is shown in figure one.
The anode can support up to four crucibles (nu creusets) every one containing a certain metal which can be deposited when positioned against the filament of cathode and when the anode high voltage is applied.
We made deposition of Cu with Co, or Ni and Fe with Cr in an alternate structure.
We will present the obtained results for the layers made of [Fe (18 A) and Cr(9 A)]40 . The magneto-resitence was measured using the four point method skematically presented in the fig.2.
The deposition conditions were the faollowing:
-The filament heating current – 25 Amperes;
-The anode potential – 1600 V for Fe deposition and 1400 V for Cr deposition.
-The arc current 100-120 mA.
-The vacuum – 10-6 torr (oil diffusion pump)
-The deposition rates: 5 A/sec for Cr,and 3 A/sec for Fe.
In the fig.3 we present the decrease of the layer resistence when increasing the magnetic field between zero value and 1.2 T.
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