Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 55, Number 9
Friday–Saturday, October 15–16, 2010; Ogden, Utah
Session K3: Condensed Matter, Thin Films |
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Chair: Ryan O'Hayre, Colorado School of Mines Room: 404B |
Saturday, October 16, 2010 11:30AM - 11:42AM |
K3.00001: Spin Wave Resonance in Permalloy Nano Films Deposited by Magnetron Sputtering Yiyan Sun, Young-Yeal Song, Mingzhong Wu It is well known that, in magnetic films with pinned surface spins, there exist standing spin wave resonance (SWR) modes across the film thickness. In films with nanometer thickness, these constrained modes have very large wave numbers and produce very high effective exchange fields and, therefore, can have a substantial influence on the magnetization dynamics and relaxation in these films as well as structures containing such films. This presentation reports on the measurement of SWR modes in Permalloy nano films and the identification of pinning mechanisms. The films were deposited by magnetron sputtering. The SWR measurements were carried out with a 17.3 GHz waveguide cavity, field modulation, and lock-in detection. The measurements indicate the following results. (1) The spins on the substrate side are partially pinned, and this pinning can be weakened or even eliminated through the use of different substrates. (2) The surface spins are unpinned. This is opposite to the general belief that the surface oxidation can give rise to the pinning of surface spins. (3) In very thin films, the resonance field for high-order modes can be extremely low due to very large SWR-associated exchange fields. [Preview Abstract] |
Saturday, October 16, 2010 11:42AM - 11:54AM |
K3.00002: Deposition of Metals via Chemical Vapor Deposition David McKenna, David Allred, Robert Davis In an effort to develop a CVD process to deposit metals on various substrates I have created a multi-gas system with a computer controlled interface. This allows the use of up to 5 different gasses as reactants or carriers for the CVD process. I have also fabricated a specialized heated [gas flow chamber wherein solid materials can be volatilized with heat and carried to the substrate by gas also heated in the chamber. I will present the design of this chamber and it's function in our current deposition process along with preliminary results of the deposition of tungsten on various substrates. [Preview Abstract] |
Saturday, October 16, 2010 11:54AM - 12:06PM |
K3.00003: Economical Atomic Layer Deposition Richard Wyman, Robert Davis, Matthew Linford Atomic Layer Deposition is a self limiting deposition process that can produce films at a user specified height. At BYU we have designed a low cost and automated atomic layer deposition system. We have used the system to deposit silicon dioxide at room temperature using silicon tetrachloride and tetramethyl orthosilicate. Basics of atomic layer deposition, the system set up, automation techniques and our system's characterization are discussed. [Preview Abstract] |
Saturday, October 16, 2010 12:06PM - 12:18PM |
K3.00004: Mapping the spatial dependency of magnetic domain memory in [Co/Pd]IrMn films Karine Chesnel, Joseph Nelson, Brian Wilcken, Eric Fullerton, Steve Kevan Magnetic memory, the ability of a material to remember its magnetic domain configuration throughout magnetization, offers potential technological interest for the data storage industry. One way to quantify the magnetic memory is to use Coherent X-ray Resonant Magnetic Scattering (XRMS) tools, at synchrotron facilities. When illuminated by coherent beam, at a specific energy, the sample produces magnetic speckle patterns. Our approach is to cross-correlate patterns recorded at different field values throughout the magnetization cycle, and at different temperatures. We have studied the return point memory (RPM) that characterizes the memory after a full cycle, and developed a q-selective correlation analysis to study the spatial dependency of the memory. We will give here an overview of different type of memory behaviors, first showing disorder induced memory in thin CoPt films and influence of roughness, then demonstrating the ability to control the magnetic memory by inducing exchange bias (1). We will see how the local exchange couplings pin the magnetic domains in the ferromagnetic layer and lead the large memory enhancement at different spatial scales. (1) K.Chesnel et al, PRB \textbf{78}, 132409 (2008) [Preview Abstract] |
Saturday, October 16, 2010 12:18PM - 12:30PM |
K3.00005: Origins of Damping in Ultra-Thin Ferromagnetic Films Lei Lu, Zihui Wang, Griffin Mead, Mingzhong Wu, Christian Kaiser, Qunwen Leng Identification of physical damping processes in magnetic materials is critical to the understanding and control of magnetization dynamics in these materials. This presentation reports on the identification and quantization of damping processes in a 7 nm-thick Ni-Co-Fe alloy film with a nonmagnetic metallic cap layer. The work was done through the use of ferromagnetic resonance (FMR) measurements and numerical analysis. The FMR measurements utilized shorted waveguides and waveguide cavities and were carried out for a wide range of polar angles from -25\r{ }to 95\r{ }and a wide frequency range from 8 GHz to 18 GHz. The results indicate that the FMR linewidth consists of a large contribution from Gilbert-type damping, a small contribution from grain-to-grain two magnon scattering, and a very small component from inhomogeneity line broadening. The obtained Gilbert damping constant is slightly larger than the intrinsic damping constant generally accepted for transition metals. The intrinsic damping is mainly associated with magnon-electron scattering processes. The small addition to the intrinsic damping is believed to be a result of the spin pumping effect. [Preview Abstract] |
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