Magnetic Data Storage Technology Research Articles

Probe-based recording technology

The invention of the scanning tunneling microscope (STM) prompted researchers to contemplate whether such technology could be used as the basis for the storage and retrieval of information. With magnetic data storage technology facing limits in storage density due to the thermal instability of magnetic bits, the super-paramagnetic limit, the heir-apparent for information storage at higher densities appeared to be variants of the STM or similar probe-based storage techniques such as atomic force microscopy (AFM). Among these other techniques that could provide replacement technology for magnetic storage, near-field optical scanning optical microscopy (NSOM or SNOM) has also been investigated. Another alternative probe-based storage technology called atomic resolution storage (ARS) is also currently under development. An overview of these various technologies is herein presented, with an analysis of the advantages and disadvantages inherent in each particularly with respect to reduced device dimensions. The role of micro electro mechanical systems (MEMS) is emphasized.

Ultrafast generation of magnetic fields in a Schottky diode.

For the development of future magnetic data storage technologies, the ultrafast generation of local magnetic fields is essential. Subnanosecond excitation of the magnetic state has so far been achieved by launching current pulses into micro-coils and micro-striplines and by using high-energy electron beams. Local injection of a spin-polarized current through an all-metal junction has been proposed as an efficient method of switching magnetic elements, and experiments seem to confirm this. Spin injection has also been observed in hybrid ferromagnetic-semiconductor structures. Here we introduce a different scheme for the ultrafast generation of local magnetic fields in such a hybrid structure. The basis of our approach is to optically pump a Schottky diode with a focused, approximately 150-fs laser pulse. The laser pulse generates a current across the semiconductor-metal junction, which in turn gives rise to an in-plane magnetic field. This scheme combines the localization of current injection techniques with the speed of current generation at a Schottky barrier. Specific advantages include the ability to rapidly create local fields along any in-plane direction anywhere on the sample, the ability to scan the field over many magnetic elements and the ability to tune the magnitude of the field with the diode bias voltage.

Fabrication of large scale periodic magnetic nanostructures

We report on the fabrication of large scale periodic magnetic nanostructures designed as possible candidates for a future application in magnetic data storage technology. The nanostructures are prepared on glass substrates by electron beam evaporation of Fe or Co onto photoresist masks, which are periodically patterned using optical interference lithography with an Ar+ laser (λ=457.8 nm) in combination with subsequent selective etching. We present our first results on the fabrication of periodic arrays of isolated magnetic dots with an average diameter of 600 nm and periodicity of 900 nm over areas of 5 cm2.

Preparation and characterization of large scale periodic magnetic nanostructures (abstract)

We report on the preparation and characterization of large scale periodic magnetic nanostructures designed as possible candidates for a future application in magnetic data storage technology. The nanostructures are prepared on glass substrates by UHV electron beam evaporation of Fe, Co, or Co/Pt onto periodically patterned photoresist masks followed by a lift-off of the photoresist. The preceding patterning process of the photoresist is achieved by using an interference lithography process in combination with subsequent selective etching. For the exposure of the photoresist, we use two different experimental setups with Ar ion lasers operating at wavelengths of 457 and 244 nm, respectively. This allows us to control diameter as well as distances between magnetic dots ranging between 300 and 3000 nm. The structural characterization of magnetic nanostructures is performed by electron microscopy as well as atomic force microscopy. Magnetic force microscopy along with additional image calculations based on dipole–dipole interaction between a magnetic tip and a magnetic dot allows for an interpretation of the magnetic properties of single magnetic dots. Accompanying work focuses on comparable nanostructures of smaller sized samples prepared by electron-beam lithography.