My 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.
Nanomagnetic transducers fabricated focused ion-beam (FIB). Left to right: 30nm wide longitudinal writer; 60nm wide perpendicular writer; ultra-sharp probe transducer with 40nm x 40nm x 10nm apex.
The current research activities are focused on applications of nanocrystalline materials and nanoscale devices for achieving extremely high density recording (above 1Terabit/in2). The current state-of-the-art in magnetic recording is 160x40x10nm magnetic features (corresponding to areal density of 100Gbin/in2) 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/in2. 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/in2 (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.
ECE4339 : Physical Principles of Solid State Devices
Prof. Dmitri Litvinov
Department of Electrical and Computer Engineering
Room N 308, Engineering Building 1
University of Houston
Houston, TX 77204-4005