Abstract
A series of Co nanocluster-assembled films with cluster sizes ranging from 4.5 nm to 14.7 nm were prepared by the plasma-gas-condensation method. The size-dependent electrical transport properties were systematically investigated. Both of the longitudinal resistivity ({rho }_{xx}) and saturated anomalous Hall resistivity ({rho }_{xy}^{A}) continuously increased with the decrease of the cluster sizes (d). The {rho }_{xx} firstly increased and then decreased with increasing the temperature for all samples, which could be well described by involving the thermally fluctuation-induced tunneling (FIT) process and scattering. The tunneling effect was verified to result in the invalidation of classical anomalous Hall effect (AHE) scaling relation. After deducting the contribution from tunneling effect to {rho }_{xx}, the AHE scaling relation between {rho }_{xy}^{A} and the scattering resistivity ({rho }_{S}) by varying the temperature was reconstructed. The value of scaling exponent γ increased with increasing Co cluster sizes. The size dependence of γ might be qualitatively interpreted by the interface and surface-induced spin flip scattering. We also determined the scaling relation between {rho }_{xy}^{A} and {rho }_{S} at 5 K by changing the Co cluster sizes, and a large value of γ = 3.6 was obtained which might be ascribed to the surface and interfacial scattering.
Highlights
Magnetic granular film, as a class of functional materials, is very attractive due to its rich fundamental phenomena and opening a new route for potential novel applications[1,2,3]
Xiong et al studied the size dependence of ρxAy and ρxx in Co-Ag granular films by changing the annealing temperature, and the scaling exponent of γ = 3.7 was obtained at 4.2 K9
We systematically studied the Co cluster sizes dependence of ρxx and ρxAy in uniform Co nanocluster-assembled films
Summary
It was obvious that RAR shown a sharper decrease than RRR with the decrease of Co cluster sizes This indicated that temperature-dependent ρxAy and ρS were affected by different physical mechanisms, and the spin flip enhanced at high density of interface and surface. Fitting the experimental data into a straight line, σxAy ∝ σS−1.6 was obtained at 5 K (σS represented the longitudinal conductivity originating from scattering), which disagreed with the universal character of the 1.6 scaling relation This result gave a strong indication that our samples was inconsistent with the unified theory, which was mainly ascribed to the surface and interfacial scattering. The longitudinal resistivity could be very well fitted by the combination of FIT process and scattering in the whole temperature range Both of ρxx and ρxAy shown a decreasing function of the Co cluster sizes due to the drop of surface and interfacial scattering.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
