Effect of interface intermixing on giant magnetoresistance in NiFe/Cu and Co/NiFe/Co/Cu multilayers

Abstract

This article reports on the important influence of the spontaneously built-in paramagnetic interfacial layers on the magnetic and magnetoresistive properties of NiFe/Cu and Co/NiFe/Co/Cu multilayers grown by magnetron sputtering. A computational simulation, based on a semiclassical model, has been used to reproduce the variations of the resistivity and of the magnetoresistance ͑MR͒ amplitude with the thickness of the NiFe, Cu, and Co layers. We showed that the compositionally intermixed layers at NiFe/Cu interfaces, which are paramagnetic, reduce the flow of polarized electrons and produce a masking on the estimated mean-free path of both types of electrons due to the reduction of their effective values, mainly for small NiFe thickness. Moreover, the transmission coefficients for the electrons decrease when Fe buffer layers are replaced by NiFe ones. This result is interpreted in terms of the variations of the interfacial intermixing and roughness at the interfaces, leading to an increase of the paramagnetic interfacial layer thickness. The effect provoked by Co deposition at the NiFe 16 Å/Cu interfaces has also been investigated. The maximum of the MR amplitudes was found at 5 Å of Co, resulting in the quadruplication of the MR amplitude. This result is partially attributed to the interfacial spin-dependent scattering due to the increase of the magnetic order at interfaces. Another effect observed here was the increase of the spin-dependent scattering events in the bulk NiFe due to a larger effective NiFe thickness, since the paramagnetic interfacial layer thickness is decreased.

Energy deposition of H and He ion beams in hydroxyapatite films: A study with implications for ion-beam cancer therapy

“…A thicker HAp film (733 nm) was also deposited on a Si(100) substrate to be characterized by the grazing incidence x-ray diffraction (GIXRD). The thicknesses and a mean density of 3.22 g/cm 3 , in good agreement with other reported values [32], were obtained by using the software package WINGIXA by Philips [49,50] to fit the x-ray specular reflectivity (XRR) curves obtained in a Rigaku diffractometer. The phase composition of the HAp thin films was characterized by GIXRD [48] at the Brazilian Synchroton Light National Laboratory, operating at 9 keV corresponding to a wavelength of 0.1377 nm, fixed incident angle θ = 0.5°and 1°, diffracted 2θ angle scanned in the range of 9°to 50°at a rate of 0.04°/point s −1 .…”

Ferromagnetic resonance and magnetization studies in exchange-coupled NiFe/Cu/NiFe structures

“…One is the fluctuation of the bilinear coupling [26,27] due to the small variations of the distance between the NiFe layers through the Cu. This could be provoked by the intermixing between NiFe and Cu at the interfaces, the latter being paramagnetic [12]. The other factor could be presence of pinholes that are able to couple directly the two magnetic layers.…”

“…The Cu layer thickness of 9 Å was chosen as to correspond to the first peak of the AF coupling, which has been precisely determined from magnetoresistance measurements [12], where magnetoresistance amplitude of 22% was obtained for Fe(90 Å )/Cu(9 Å )/ [(NiFe(16 Å )/Cu(9 Å )] 20 sample grown in the same conditions.…”

Energy Loss Function of Solids Assessed by Ion Beam Energy-Loss Measurements: Practical Application to Ta2O5

“…It was measured afterward using the X-ray reflectivity technique and the software package WinGixa from Philips. 61,62 Besides the thickness, the root-mean-square roughness and mass density of each film were deduced from the fits. The thicknesses t of the Ta 2 O 5 films were 25 (1), 36 (1), 45 (1), 58 (1), 75 (1), 95 (2), 110 (3), and 173 (3) nm.…”