Influence of an interface domain wall on spin-valve giant magnetoresistance

Thomas Hauet (1) , F Montaigne (1) , M. Hehn (1) , Y Henry (2) , S Mangin (1)

1 IJL - Institut Jean Lamour
2 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg

The magnetotransport properties of a Gd 40 Fe 60 / Gd 10 Fe 90 / Cu/ Gd 40 Fe 60 spin-valve based on amorphous ferrimagnetic GdFe layers are reported. The Gd 40 Fe 60 / Gd 10 Fe 90 bilayer is an exchange spring structure that allows an interfacial domain wall to be controlled by an applied field. As this domain wall is nucleated, compressed, and annihilated, changes in the spin-valve current-in-plane magnetoresistance are observed. After separating the various magnetoresistance contributions we could deduce the effect of the interface domain wall on both the giant and anisotropic magnetoresistances. Several architectures have been used to attain a better understanding of giant magnetoresistance ͑GMR͒ phenomenon. This important activity has been driven by its strong implications for magnetic data storage devices and sensors. 1 In most GMR structures, the magnetic electrodes are sufficiently thin so that the magnetization could be considered as uniform across the thickness of the ferromagnetic layers. However, it is commonly known that GMR originates from a combination of interfacial and bulk spin-dependent scattering. Therefore, one may expect that a vertically nonuniform magnetization state of the magnetic layer would reflect in its GMR response. One way to induce a perpendicular-to-layer nonuniform magnetic configuration in a spin valve consists in replacing one of the magnetic electrodes with an exchange-coupled bilayer system. 2–4 in which a planar interface domain wall ͑iDW͒ may be tuned. In the present letter, we report on the magnetoresistance properties of such a modified spin-valve structure, Gd 40 Fe 60 / Gd 10 Fe 90 / Cu/ Gd 40 Fe 60 , where Gd x Fe 1−x are ferri-magnetic alloys. The alloys' magnetic properties ͑magnetiza-tion, anisotropy, exchange stiffness, etc.͒ can easily be tuned by changing composition 5 and/or growth conditions. 6 Such materials have already been used in spin-valve structures 7,8

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Thomas Hauet, F Montaigne, M. Hehn, Y Henry, S Mangin. Influence of an interface domain wall on spin-valve giant magnetoresistance. Applied Physics Letters, 2008, ⟨10.1063/1.3041640⟩. ⟨hal-01345244⟩