Considerations in the design of probe heads for 100 Gbit/in/sup 2/ recording density

Thin film perpendicular playback yoke-GMR heads capable of reading at a density of 100 Gbit/in/sup 2/ have been designed using 3D boundary element reciprocity modeling. Two basic head types are considered, a single-pole and a ring-type geometry. The influence on the playback voltage and D/sub 50/ of the throat height, fly height, and permeability are studied. Isolated pulse response, roll-off curves, and off-track profiles are calculated. Media with and without a soft underlayer are also considered. The simulations show that of the designs studied the ring head in combination with the media without a soft underlayer has playback properties suitable for this density

Physics of perpendicular magnetic recording: writing process

Using 3D-boundary element modeling, guidelines for designing an ultra-high density perpendicular system were defined. Both geometrical and material influences were investigated. The theoretical principles developed to choose dimensions and materials were experimentally verified using a wafer test structure and spin-stand experiments with a 60 nm wide focused ion beam trimmed head

Multiple magnetic image reflection in perpendicular recording

Three-dimensional modeling was performed to show that integration of a single-pole head with a relatively wide leading pole and a medium with a soft underlayer (SUL) gives rise to the field multiplication effect due to the "multiple image reflection" of the flux. generated in the hard-layer region located between the leading pole and the SUL. Magnetic force microscopy and spin-stand experiments were utilized to support the theory

Recording heads with track widths suitable for 100 Gbit/in/sup 2/ density

Longitudinal recording in its conventional form has been projected to suffer from superparamagnetic instabilities at a density of approximately 40 GbiL/in2 [I]. It is believed that changing the bit cell aspect ratio will extend the superparamagnetic limit of magnetic recording. Also, perpendicular recording might be extensible to higher densities due to a thicker optimum recording layer [2]

Electron Transport in Ferromagnetic Nanostructures

The proposal of logic- and memory devices based on magnetic domain-wall motion in nanostructures created a great demand on the understanding of the dynamics of domain walls. We describe the controlled creation and annihilation of domain walls by Oersted-field pulses as well as their internal dynamics during motion. Electric measurements of the magnetoresistance are utilized to identify permanent- or temporal creation and continuous motion of domain walls initiated by nanosecond short field pulses in external magnetic fields. The injection of domain walls into nanowires with control of their magnetic pattern (transverse or vortex), their type (head-to-head or tail-to-tail magnetization orientation) and their sense of magnetization rotation (clockwise or counter clockwise chirality) is reliably achieved. Influencing the creation process of consecutively created domain walls to obtain multiple walls inside one wire or to mutually annihilate the walls is found to be possible by changes of magnetic field parameters. The time structure of the creation process is analysed by time-resolved transmission X-ray microscopy. After complete formation wall transformations are observed above a critical driving field known as the Walker breakdown. Internal excitations of vortex domain walls are also found in low field motion. A strong interplay between internal dynamics and the macroscopic motion is identified