FastMag is a computational framework for simulating magnetization/spin dynamics in ultra-complex magnetic systems. FastMag can handle complex structures meshed over tetrahedral meshes as large as 150 million elements. It allows modeling a host of magnetic systems, such as magnetic recording heads, media, and arrays of magnetic nanoparticles.
The efficiency of FastMag derives from fast computational methods for effective field calculation and time integration as well as their efficient implementations on massively parallel computing systems.
We demonstrated a GPU implementation of the widely used Object Oriented Micromagnetic Framework (OOMMF), showing up to 70x GPU-CPU speed-up with the latest GPUs. The implementation is such that most of the user-related OOMMF components are unchanged and only the lower-level modules are ported to GPU. This allows OOMMF users to run their models as before but at greater speed.
OOMMF is a project in the Applied and Computational Mathematics Division (ACMD) of ITL/NIST, aimed at developing portable, extensible public domain programs and tools for micromagnetics. GPU OOMMF was developed in collaboration with Dr. Michael J. Donahue, National Institute of Standards and Technology (NIST).
We use our codes to study magnetization dynamics mechanisms in magnetic nanostructured materials. These mechanisms include dynamics of magnetization reversal in composite and patterned media for ultra-high density magnetic recording, composite media for microwave assisted magnetic recording, heat-assisted magnetic recording, as well as magnetic random access memory elements. Our interests also are in the study of spin transfer torque phenomena and spin waves. This research is conducted in collaboration with the research groups in the Center for Memory and Recording Research at UCSD as well as our industrial partners.
1. J.E. Martin, M.V. Lubarda, V. Lomakin, P.O. Jubert, "Effect of Thermal Fluctuations on the Performance of Particulate Media". Magnetics, IEEE Transactions on. Jul. 2013.
2. A. Singh, S. Gupta, M. Kuteifan, M. Lubarda, V. Lomakin, O. Mryasov, "Effect of Interlayer Exchange Coupling Parameter on Switching Time and Critical Current Density in Composite Free Layer". Journal of Applied Physics. May, 2014.
3. M. A. Escobar, M. V. Lubarda, S. Li, R. Chang, B. Livshitz, and V. Lomakin, “Advanced Micromagnetic Analysis of write head dynamics using FastMag,” IEEE Transactions on Magnetics. 2012 May;48(5):1731-7.
4. I. Yulaev, M. Lubarda, S. Mangin, V. Lomakin, and Eric E. Fullerton, “Spin-transfer-torque reversal in perpendicular anisotropy spin valves with composite free layers,” Applied Physics Letters, vol. 99, p. 132502, 2011.
5. M. Lubarda, S. Li, B. Livshitz, E. E. Fullerton, and V. Lomakin, “Antiferromagnetically-coupled capped bit patterned media for high-density magnetic recording,” Applied Physics Letters, vol. 98, p. 012513, 2011.
6. M. Lubarda, S. Li, B. Livshitz, E. E. Fullerton, and V. Lomakin, “Reversal in bit patterned media with vertical and lateral exchange,” IEEE Transactions on Magnetics, January, 2010, vol. 47, no. 1, pp. 18-25, 2011.
The investigation of the photonic and magnetic nanostructures is based on the development of sophisticated analytical models and efficient numerical. We develop efficient analytical and numerical methods to compute electromagnetic/optical/magnetic fields in complex configurations. Many of these methods are based on integral formulation methodology.
Our study of electromagnetic, optical, and magnetic fields in complex structures relies on the developments of efficient analytic and computational methods. In terms of computational methods, we are currently most interested in integral equation type approaches. These approaches are developed for computing electromagnetic field in systems comprising finite and infinite periodic distributions of scatterers in free space or in layered medium backgrounds.
1. R. Chang, V. Lomakin, "Quadrilateral Barycentric Basis Functions for Surface Integral Equations", Antennas and Propagation, IEEE Transactions on. Dec. 2013.
2. R. Chang, V. Lomakin, "A method for identifying global loop basis functions for surface integral equations", Antennas and Propagation Society International Symposium (APSURSI), Jul. 2014.
Out interests are to study various electromagnetic phenomena supported by isolated nano-scale metallic/plasmonic or dielectric elements as well as arrayed elements residing in free space or coupled with structured and layered metal-dielectric surfaces. The study is geared towards identifying novel applications of the investigated structures and phenomena including subwavelength lasers as well as wave guiding and focusing structures for surface microscopy.
1. V. Lomakin, Y. Fainman, Y. Urzhumov, and G. Shvets, "Doubly negative metamaterials in the near infrared and visible regimes based on thin films," Optics Express, vol. 14, n. 23, pp. 11164-11177, 2006.
2. V. Lomakin, Y. Fainman, Y. Urzhumov, and G. Shvets, "Optical metamaterials based on thin metal films: From negative index of refraction to enhanced transmission," SPIE, San Diego, California, August 2007 (invited).
3. A. Mizrahi, V. Lomakin, B.A. Slutsky, M.P. Nezhad, L. Feng, and Y. Fainman, "Low threshold gain metal coated laser nanoresonators," Optics Letters, vol. 33, no. 11, pp. 1261-1263, 2008.
4. L. Feng, K.A. Tetz, B. Slutsky, V. Lomakin, and Y. Fainman, "Fourier plasmonics: Diffractive focusing of in-plane surface plasmon polariton waves", Applied Physics Letters, vol. 91, 081101, 2007.
5. D. Van Orden, Y. Fainman, and V. Lomakin, "Optical waves on nano-particle chains coupled with metal-dielectric surfaces," Conference on Lasers and Electro-Optics (CLEO/QELS), San Jose, California, May 2008.
6. V. Lomakin, M. Lu, and E. Michielssen, "Optical wave properties of nano-particle chains coupled with a metal surface," Optics Express, vol. 15, pp. 11827-11842, 2007.
7. V. Lomakin, S.Q. Li, and E. Michielssen, "Manipulation of stop-band gaps of periodically perforated conducting plates," IEEE Microwave and Wireless Components Letters, vol. 15, no. 12, pp. 919-921, 2005.
8. V. Lomakin and E. Michielssen, "Enhanced transmission through metallic plates perforated by arrays of subwavelength holes and sandwiched in between dielectric slabs," Physical Review B, vol. 71, no. 23, pp. 235117 - 1-10, 2005.
9. V. Lomakin, S. Li, and E. Michielssen, "Plane wave transmission through metal plates perforated by periodic arrays of through-holes of subwavelength coaxial cross-section," Microwave and Optical Technology Letters, vol. 49, no. 7, pp. 1554-1558, 2007.
10. V. Lomakin and E. Michielssen, "Beam transmission through periodic sub-wavelength hole structures," IEEE Transactions on Antennas and Propagation, vol. 55, no. 6, pp. 1564-1581, 2007.
11. V. Lomakin and E. Michielssen, "Transmission of transient plane waves through perfect electrically conducting plates perforated by periodic arrays of subwavelength holes," IEEE Transactions on Antennas and Propagation, vol. 54, no. 3, pp. 970-984, 2006.
12. V. Lomakin, N.W. Chen, S. Q. Li, and E. Michielssen, "Enhanced transmission through two-period arrays of sub-wavelength holes," IEEE Microwave and Wireless Components Letters, vol. 14, no. 7, pp. 355-357, 2004.