Bulletin of the American Physical Society
Fall 2009 Meeting of the Four Corners Section of the APS
Volume 54, Number 14
Friday–Saturday, October 23–24, 2009; Golden, Colorado
Session F4: Physics of Data Storage |
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Chair: Christoph Boehme, University of Utah Room: Green Center 263 |
Saturday, October 24, 2009 8:00AM - 8:24AM |
F4.00001: Commercial Holographic Data Storage Invited Speaker: An overview of the laser, servo, recording, and media technologies for a 300GB holographic, archival data storage product is presented. [Preview Abstract] |
Saturday, October 24, 2009 8:24AM - 8:36AM |
F4.00002: Carbon Coated Tellurium Film for Optical Data Storage Jonathan Abbott, Travis Niederhauser, Erik Bard, Mike Miller, Mark Worthington, Doug Hansen, Guilin Jiang, Robert Davis, Richard Vanfleet, Matthew Linford A highly durable optical disk has been developed for data archiving. This optical disk uses tellurium as the write layer and carbon as a dielectric and oxidation prevention layer. The sandwich style CTeC film was deposited on polycarbonate and silicon substrates by plasma sputtering. These films were then characterized with SEM, TEM, EELS, ellipsometry, ToF-SIMS, etc, and were tested for writability and stability. Results show the films were uniform in physical structure, able to form pits, and promise longer lifetimes than currently available media. Data was written to a disk and successfully read back in a commercial DVD drive. [Preview Abstract] |
Saturday, October 24, 2009 8:36AM - 8:48AM |
F4.00003: From exchange coupling to magnetic memory: how domains remembers at nanoscale Karine Chesnel, Joseph Nelson, Brian Wilcken, Steve Kevan, Matthew Carey, Eric Fullerton 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. The light is tuned to resonant edges of magnetic element to optimize the magneto-optical contrast. When illuminated by coherent beam, the sample produces 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 domain in the ferromagnetic layer and lead the large memory enhancement at different spatial scales. \\[0pt] [1] K.Chesnel et al, PRB \textbf{78}, 132409 (2008) [Preview Abstract] |
Saturday, October 24, 2009 8:48AM - 9:00AM |
F4.00004: Spatial Dependency of Magnetic Domain Memory in Exchange Bias Films Joseph Nelson The properties of magnetic materials have become increasingly important to many applications, including high-density magnetic memory storage. In recent years, thin films have been developed which exploit F/AF exchange bias, effectively ``freezing'' the microscopic magnetic domain patterns in a desired orientation [1]. We have quantified magnetic memory---the degree to which domain patterns resume their prior orientation after magnetic saturation---in these films using speckle analysis of X-Ray Resonant Magnetic Scattering (XRMS) data. The correlation between domain patterns is directly related to the correlation between their respective speckle patterns. We have measured the magnetic memory of these samples as a function of applied field, number of major field cycles, and spatial scale. We have observed very high correlations, exceeding 95{\%} in many cases, even after repeated field cycles. We have also developed a q-vector selective analysis which reveals specific general features in the spatial dependencies of these correlations. \\[4pt] [1] K.Chesnel et al, PRB \textbf{78}, 132409 (2008) [Preview Abstract] |
Saturday, October 24, 2009 9:00AM - 9:12AM |
F4.00005: Vortex-in-nanodot potential energy Gary Wysin Vortex states in a thin circular magnetic nanodot are studied using auxilary constraining fields as a way to map out the potential energy space of the vortex, while avoiding a rigid vortex approximation. In the model, isotropic Heisenberg exchange competes with the demagnetization field caused both by surface and volume magnetization charge density. The system energy is minimized while applying a constraint on the vortex core position, using Lagrange's method of undetermined multipliers. The undetermined multiplier is seen to be the external field needed to hold the vortex core in place at any desired radial distance $r$ from the dot center. This auxilary field is applied only in the core region of the vortex. For a uniform nanodot, the potential energy is found to be very close to parabolic with $r$, as in the rigid vortex approximation, while the constraining field increases linearly with $r$. Effects of nonmagnetic holes in the medium can also be estimated and compared with alternative descriptions. Especially, the local depth of the potential well produced by a hole can be found. [Preview Abstract] |
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