L.N. He

Size and shape effects of patterned polycrystalline islands

Patterned polycrystalline cobalt islands with different sizes and shapes have been simulated by a micromagnetic simulator. An elliptic shape is found to be preferred for patterned islands to form a uniform single domain demagnetised state and have sharper squareness compared with square islands. Therefore, in a single-bit-per-island recording system, the elliptic islands could lead to a stable state and a predictable overwrite process and act independently even in a closely packed arrays.

Interaction between track and linear densities

In this work, we report a micromagnetic simulation study on narrow track recording characteristics in thin film media. It is found that, arising from interaction between track density and linear density, a sub-micron trackwidth imposes a limitation on linear density. In order to achieve a high track density greater than 75,000 tpi while keeping the required high linear density, eliminating the interaction between track and linear densities is needed, by either optimized medium design or head design.

Faster And Denser Spin-Tunneling Random Access Memory (STram)

The spin tunneling junctions Co/Al/sub 2/O/sub 3//Ni/sub 80/Fe/sub 20/ provide an excellent means of storing a binary datum in the hard component (Co), and sensing its remanent state by switching the soft component (NiFe) in such a way that the magnetic state of the hard component remains unaltered. In this paper, it is clarified by a dynamic model that the switching is caused by the incoherent rotation of the magnetization in the fine thin film pattern and the read access time for a micro-structured spin tunneling with area of 0.256 /spl mu/m/spl times/0.256 /spl mu/m is 0.9 ns. In addition, a magnetic flux closure design was found to reduce the crosstalk by about a factor of five, compared with a conventional keeper-less design, which will be the most favored approach for achieving 10/sup 9/ bits/cm/sup 2/ areal density.

Sensors for dynamic characterisation of magnetic storage systems

The areal (surface area density of bits) storage density of magnetic hard disks is continually increasing, with typical available commercial storage densities being around 10Gbits/in2. It is predicted that densities in excess of 40Gbits/in2 will be possible before the year 2003. A number of key issues arise from this development, such as the need to determine and control accurately the dynamic flying height (z‐axis) of the read‐write head, which is affected by the apparent distortion of the disk surface due to rotation‐induced disk resonance. As a result of the increasing storage density the positional control of the head in the plane of the disk (x‐y plane) also becomes more critical. This paper deals generally, but with a particular emphasis on optical and piezoelectric sensors used in our laboratory for characterisation of storage media and systems.

STORAGE MECHANISM OF SPIN-TUNNELING JUNCTIONS

Abstract This paper concerns a microstructured spin-tunneling junction in which the minor loops slope has a dependency on its past magnetic histories. The above storage mechanism inspired the authors to design and fabricate a new type of solid state spin-tunneling random access memory. This memory operates on the general principle of storing a binary datum in the `hard’ magnetic component and sensing its remanent state by switching the `soft’ magnetic component in such a way that the magnetic state of the `hard’ component remains unaltered.

Read-while-write operation in magnetic recording

Abstract This investigation relates to magnetic transducing apparatus (magnetic tape units and potentially magnetic disk units) for use in read-while-write (RWW) mode. We shall confine ourselves here to the most important part of the noise, that resulting from field interaction. This type of coupling is called “crossfeed” noise and it is caused by radiation across the recording surface of the magnetic transducer head due to the electromagnetic field. As a result, a favoured scheme to suppress the crossfeed noise from the write head in a RWW head is to employ a dual-MR sensor instead of a conventional SAL MR sensor. The measured signal-crossfeed ratio (SCR) agrees reasonably with the theoretical predictions.