-• Research and Academics

Dr. Litvinov's research interests span a range of topics related to the development and applications of novel magnetic materials and devices at nanoscale dimensions. These include micro- and nanomagnetic materials and devices directly related to the current and future magnetic storage technologies such as disk drive storage, probe storage based on MEMS and MRAM. Among the investigated issues are fabrication and device physics of magnetic probe heads at nanoscale dimensions (the recording heads with dimensions down to few tens of nanometers have been routinely fabricated using focused ion-beam nanofabrication techniques); development and characterization of nanocrystalline materials for advanced recording media applications; micromagnetic behavior of soft magnetic materials; recording properties of nanocrystalline alloy and superlattice-based media materials; recording processes at nanoscale dimensions, etc. Record track densities in excess of 400ktpi (~60nm track width) were demonstrated using above-mentioned nanoprobe recording heads and specially prepare media. The micromagnetic behavior of magnetic ‘nanotubes’ was for the first time experimentally observed.

The current research activities are focused on applications of nanocrystalline materials and nanoscale devices for achieving extremely high density recording (above 1Terabit/in 2). The current state-of-the-art in magnetic recording is 160x40x10nm magnetic features (corresponding to areal density of 100Gbin/in 2) recorded into a magnetic recording medium. The individual magnetic grains forming the recording medium are ~9nm in diameter. At these dimensions, the conventional recording schemes employed today are rapidly approaching the fundamental (superparamagnetic) limit in areal bit density, above which the recording data become unstable. It is widely believed that longitudinal recording will run out of steam at approximately 200Gbin/in 2. Perpendicular magnetic recording will enable to sustain the current great strides in technological advances for the next several generations of mass storage solutions. The technology is technically the closest alternative to conventional longitudinal recording, while it is capable of extending the superparamagnetic density limit beyond what is achievable with longitudinal recording. The recording densities above 1Terabit/in 2 (recording features as small as 50x12x10nm) are conceivable utilizing perpendicular recording. To support such a nanoscale technology, major innovations in both magnetic recording heads and media are necessary.

Research Web Site: http://www.uh.edu/cns/litvinov/index.htm

-• Selected Publications

S. Khizroev, Y. Hijazi, N. Amos, D. Doria, A. Lavrenov, R. Chomko, T.M. Lu, D. Litvinov, “Three-Dimensional Magnetic Recording: An Emerging Nanoelectronic Technology,” Journal of Nanoelectronics and Optoelectronics 1, pp.1-18 (2006).

V. Parekh, A. Ruiz, P. Ruchhoeft, H. Nounu, D. Litvinov, and J. C. Wolfe, “Estimation of scattered particle exposure in ion beam aperture array lithography,” J. Vac. Sci. Techn. B 24 (6), pp. 2915-2919 (2006).

D. Smith, Ch. E., S. Khizroev, D. Litvinov, “The Influence of Bit Patterned Medium Design and Imperfections on Magnetoresistive Playback,” IEEE Transactions on Magnetics, 42 (10), pp. 2285-2287 (2006).

S. Khizroev, Y. Hijazi, N. Amos, R. Chomko, D. Litvinov, “Physics considerations in the design of three-dimensional and multilevel magnetic recording,” Journal of Applied Physics, 100, Art No. 063907 (2006).

E. Ch. D. Smith, S. Khizroev, D. Weller, D. Litvinov, “Micromagnetics of Magnetization Reversal in Patterned Magnetic Recording Medium,” IEEE Transactions on Magnetics, 42 (10),  pp. 2411-2413  (2006).

J.D. Dutson, D. Litvinov, M.R.J. Gibbs, Y. Inaba, H. Muraoka, K. O’Grady, “Magnetization reversal in media with perpendicular anisotropy,“ Journal of Magnetism and Magnetic Materials, 304(1), 51-54 (2006).

Y. Hijazi, R. Ikkawi, N. Amos, A. Lavrenov, D. Doria, N. Joshi, R. Chomko, D. Litvinov, S. Khizroev, “Patterned Soft Underlayers for Perpendicular Media,” IEEE Transactions on Magnetics, 42 ( 10),  pp. 2375-2377 (2006).

S. Khizroev, Y. Hijazi , N. Amos , R. Chomko , D. Litvinov, ”Physics Consideration in the Design of Three-dimensional and Multi-level Magnetic Recording,” Journal of Applied Physics, 99 (11), Art. No. 113901 (2006).

E. Chunsheng, D. Smith, E. Svedberg, S. Khizroev, D. Litvinov, “Combinatorial Synthesis of Co/Pd Magnetic Multilayers,” Journal of Applied Physics, 99, Art. No. 113901 (2006).

V. Parekh, Ch. E, D. Smith, A. Ruiz, J.C. Wolfe, P. Ruchhoeft, E. Svedberg, S. Khizroev, D. Litvinov, “Fabrication of High Anisotropy Nanoscale Patterned Magnetic Recording Medium for Data Storage Applications,” Nanotechnology, 17, pp. 2079-2082 (2006).

D. Litvinov, and S. Khizroev, “Perpendicular Magnetic Recording: Playback,” Applied Physics Reviews in Journal of Applied Physics, Vol. 97, No. 7, pp. 1–12, 2005.

Smith, D., Ch. E, S. Khizroev, and D. Litvinov, “Magnetoresistive Playback Heads for Bit-patterned Medium Recording Applications,” Journal of Applied Physics, Vol. 99, Art. No. 014503, pp. 1–7, 2005.
 
R. Chomko, D. Litvinov and S. Khizroev, “A Nanoscale Transducer for Perpendicular Magnetic Recording,” Applied Physics Letters, Vol. 87, Art. No. 162503, pp. 1–3, 2005.

E. Chunsheng, D. Smith, S. Khizroev, D. Weller, J. Wolfe, and D. Litvinov, “Physics of Patterned Medium Recording: Design Considerations,” Journal of Applied Physics, Vol. 98, No. 2, Art. No. 024505, pp. 1–8, 2005.

S. Khizroev, Y. Hijazi, R. Chomko, S. Mukherjee, R. Chantrell, X. Wu, R. Carley, and D. Litvinov, “Focused-ion-beam-fabricated Nanoscale Magnetoresistive Ballistic Sensors,” Applied PhysicsLetters, Vol. 86, No. 4, Art. No. 042502, pp. 1–3, 2005.

D. Litvinov and S. Khizroev , "Orientation-Sensitive Magnetic Force Microscopy for Future Probe Storage Applications," Applied Physics Letters 81(10), 1878-1880 (2002) [Editor's choice in the AIP Virtual Journal of Nanoscience & Technology, Vol. 6(11), Sept. 2002].

S. Khizroev, D.A. Thompson, M.H. Kryder, D. Litvinov, "Direct Observation of Magnetization Switching in Focused Ion-beam Fabricated Nanotubes," Applied Physics Letters 81(12), 2256-2257 (2002) [Editor's choice in the AIP Virtual Journal of Nanoscience & Technology, Vol. 6(12), Sept. 2002].

D. Litvinov and S. Khizroev, "Focused Ion Beams in Future Nanoscale Probe Recording," Nanotechnology 13, 179-184 (2002).

D. Litvinov and S. Khizroev , "Overview of Magnetoresistive Probe Heads for Nanoscale Recording Applications," Journal of Magnetism and Magnetic Materials 264(2-3), 275-283, 2002.

J.T. Wolfson, J.A. Bain, S. Khizroev , and D. Litvinov, "Dynamic Kerr Imaging of Soft Underlayer for Perpendicular Recording Applications," (invited) Journal of Applied Physics 91(10), 8665-8669 (2002).

D. Litvinov, J. Wolfson, J. Bain, R.W. Gustafson, M.H. Kryder, and S. Khizroev, "Narrow Gap Single Pole Heads," IEEE Transactions on Magnetics, 38(5), 2253-2255 (2002). 

D. Litvinov, M.H. Kryder, and S. Khizroev , "Recording Physics of Perpendicular Media: Hard Layers," Journal of Magnetism and Magnetic Materials 241(2-3), 453-465 (2002).

D. Litvinov, J.Wolfson, J.A. Bain, R.W. Gustafson, M.H. Kryder, S. Khizroev, "The Role of the Gap in Single Pole Heads in Perpendicular Recording," IEEE Transactions on Magnetics 38(4), 1658-1663 (2002).

D. Litvinov, T. Roscamp, T. Klemmer, M. Wu, J.K. Howard, S. Khizroev , "Co/Pd Multilayers for Perpendicular Recording Media," MRS Proceedings 674, T3.9 (2001). 

D. Litvinov, R. Chomko, G. Chen, L. Abelmann, K. Ramstock, and S. Khizroev, "Micromagnetics of a Soft Underlayer," IEEE Transactions on Magnetics 36(5), 2483 (2000).