Giant magnetoresistive effect (GMR) in nanostructured materials made of magnetic (M) and non-magnetic (NM) species is ascribed to spin-dependent scattering (SDS) at the M/NM interface [1]. It has recently been shown that this effect appears even when the size of the magnetic regions goes to zero, i.e. the SDS is observed for M clusters made of a few atoms [2]. In this work, we investigate how the GMR efficiency, γ, i.e. the change in GMR for a unit change of magnetisation, varies as we reduce the size of SDS centres, i.e. as we start from a nanogranular magnetic system and we progres-sively reduce grain size. We study this topic in FexAg100-x co-sputtered thin films. Along with the reduction, the system first displays dipolar magnetic in-teractions and then it enters a frustrated regime. When the system undergoes this transition, shows a maximum, so we focus on the corresponding struc-tural modifications. The volume relative Fe content, x, ranged from 8 up to 40 and was measured with Rutherford Backscattering Spectrometry. The evolution of Fe atoms con-figuration was studied with magnetisation data recorded in the zero-field and the field cooled (ZFC/FC) configurations as well as using X-Ray diffraction measurements. GMR data recorded at 4 and 300 K as a function of x will be presented and compared with the corresponding samples magnetic structure evolution deduced from ZFC/FC and X-Ray data. [1] P. M. Levy, Sol. Stat. Phys. 47, 367 (1994) [2] P. Allia et al., Phys. Rev. B 67, 174412 (2003)
GMR effect across the transition from diluted to granular-like effect scattering centers
SPIZZO, Federico;RONCONI, Franco;SACERDOTI, Michele;TAMISARI, Melissa
2007
Abstract
Giant magnetoresistive effect (GMR) in nanostructured materials made of magnetic (M) and non-magnetic (NM) species is ascribed to spin-dependent scattering (SDS) at the M/NM interface [1]. It has recently been shown that this effect appears even when the size of the magnetic regions goes to zero, i.e. the SDS is observed for M clusters made of a few atoms [2]. In this work, we investigate how the GMR efficiency, γ, i.e. the change in GMR for a unit change of magnetisation, varies as we reduce the size of SDS centres, i.e. as we start from a nanogranular magnetic system and we progres-sively reduce grain size. We study this topic in FexAg100-x co-sputtered thin films. Along with the reduction, the system first displays dipolar magnetic in-teractions and then it enters a frustrated regime. When the system undergoes this transition, shows a maximum, so we focus on the corresponding struc-tural modifications. The volume relative Fe content, x, ranged from 8 up to 40 and was measured with Rutherford Backscattering Spectrometry. The evolution of Fe atoms con-figuration was studied with magnetisation data recorded in the zero-field and the field cooled (ZFC/FC) configurations as well as using X-Ray diffraction measurements. GMR data recorded at 4 and 300 K as a function of x will be presented and compared with the corresponding samples magnetic structure evolution deduced from ZFC/FC and X-Ray data. [1] P. M. Levy, Sol. Stat. Phys. 47, 367 (1994) [2] P. Allia et al., Phys. Rev. B 67, 174412 (2003)I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
