| AVS 60th International Symposium and Exhibition | |
| Magnetic Interfaces and Nanostructures | Tuesday Sessions |
| Session MI-TuP |
| Session: | Magnetic Interfaces and Nanostructures Poster Session |
| Presenter: | K.M. Stevens, North Carolina State University |
| Authors: | K.M. Stevens, North Carolina State University L. Pan, North Carolina State University J. Krim, North Carolina State University |
| Correspondent: | Click to Email |
The study of magnetic friction provides an opportunity to access bulk properties of the material and internal dissipation pathways. This gives benefits beyond that of surface studies, which assume a uniform substrate response and typically access phononic, conduction and charging pathways. This technique has been used successfully to study superconductivity-dependent friction [1,2] and nonhomogeneous magnetic microstructures[3-5].
We study gold-nickel alloys, as these provide an interesting spectrum of bulk magnetic properties. Samples with 5-20% nickel alloyed with gold were deposited as a homogenous solid-solution or as a two-phase FCC solid through the modification of annealing procedures. The solid solution is known to be paramagnetic for concentrations below 35% Ni [6], while the two phase solid maintains domains of ferromagnetism within bulk gold. These materials have been deposited onto a quartz crystal microbalance to allow properties to be monitored continuously by measuring the frequency and amplitude of the oscillator [7].
The two-phase Ni/Au material has demonstrated unique properties. Prior work has shown this to be an exceptional candidate for MEMS electrodes [8]. This work explores the impact of the bulk inhomogeneity. We have observed a “flexing” effect due to the application of an external magnetic field on two-phase alloy samples, which is measured as a discrete decrease of oscillator amplitude synchronized with the applied field; the effect is not seen on the solid solution samples of the same nickel-gold composition. The results are consistent with the formation of internal shear waves around the domains of nickel within bulk gold. An internal degree of freedom at the grain boundaries may decrease friction even in the absence of an external magnetic field.
Funding provided by NSF DMR.
[1] I. Altfeder and J. Krim, J. Appl. Phys. 11 (2012)
[2] M. Highland and J. Krim, Phys. Rev. Lett. 96 (2006)
[3] M. Wünsche et al., Z. Phys. Chem., 208, 225-238 (1999)
[4] G. Yu et al., Rev. Sci. Inst. 78, 065111 (2007)
[5] G. Yu et al., J. App. Phys. 104, 043908 (2008)
[6] A.R. Kaufmann et al., Rev. Mod. Phys. 17, 1 (1945)
[7] J. Krim, Advances in Physics, 61, 3, 155-323 (2012)
[8] L. Pan, Ph.D. Thesis, North Carolina State University (2011)