Negative spin-valve effect in Co65Fe35/Ag/(Co65Fe35)50Gd50 trilayers
Résumé
A minimum of the magnetoresistance under low fields has been observed with a Co 65 Fe 35 /Ag/ Co 65 Fe 35 50 Gd 50 trilayer at 4.2 and 300 K. This negative spin-valve effect is explained by the scattering of the conduction electrons by the Co or Fe moments included in two different structures: a polycrystalline Co 65 Fe 35 and an amorphous one Co 65 Fe 35 50 Gd 50. The Gd moments allow one to control the magnetic configuration of the transition-metal moments of the layers but are inefficient for the magnetoresistance. This interpretation is confirmed by measurements using high pulsed fields.
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