Search

Perpendicular magnetic recording at high areal densities and high data rates has been studied. Using ring heads and perpendicular media with soft underlayer, we have successfully demonstrated the areal density of 60 Gb/[in.sup.2] at the corresponding ultrahigh-linear density of 750 kbpi, a bit-aspect ratio (BAR) of 9.4, and a data rate of 300 Mb/s. Comparing the BAR of 5.7 in our recent 63.2 Gb/[in.sup.2] demonstration on longitudinal media, a larger BAR has been demonstrated with present perpendicular recording system. We have also demonstrated the data rate capability of 1 Gb/s by using both ring heads and modified-single-pole heads on perpendicular media with soft underlayer. Finally, a comparison of high-data-rate recording between ring heads and single pole heads has shown that neither magnetic viscosity nor gyromagnetic switching in perpendicular media is the limiting mechanism for magnetic recording at data rates as high as 1 Gb/s. Index Terms--Finite element model, high-data-rate magnetic recording, perpendicular recording.

Research into the response of the free layer with a parallel hard bias has involved simulating tunneling magnetoresistance films and devices. It was found that the tunneling magnetoresistance film has hysteresis in the response of the free layer largely because of the multigrain properties of the parallel magnet.

The CoZrCr alloy for high speed write heads is discussed. It is shown that the soft magnetic properties of CoZrCr amorphous alloy was achieved on sloped surfaces with 75 V substrate bias. These films possess high saturation magnetization at 13.6 kG and high resistivity at 90 micro-ohm-cm. These films also exhibited improved magnetic properties on sloped surfaces and improved corrosion properties via deposition at higher power.

The use of ion beam deposition (IBD) techniques to prepare Cr/CoCrPt bilayers for hard bias applications in giant/anisotropic magnetoresistive (GMR/AMR) recording heads is discussed. Results show that IBD provides good control of read track width and sensor layer stabilization for high density GMR/AMR recording heads. Tuning the ion beam deposition angle can also be used to manipulate the structural and magnetic properties of Cr/CoCrPt films.

A study was conducted to analyze the influence of angular biasing on the magnetic characteristics of spin-valve devices. Twenty-four pairs of unshielded spin-valve devices were fabricated. Experimental results indicated the possibility of increasing the magnetoresistance ratio by more than a factor of 2 by initializing the magnets in a direction other than along the free layer easy axis.

A thermal scanning microscope has been used to characterize the temperature of the different constituents of a thin film recording head under bias conditions. It shows that the temperature rise is highly concentrated in the current-biased read sensor. The results confirm calculations showing that most of the heat is dissipated through the shields, with the slider substrate acting as a heat sink. They also indicate that in SAL type AMR heads, the AMR layer is hotter than the SAL.

In this paper, we will report a read-only spin valve that has a trackwidth of 1.4 [[micro]meter], a read gap of 0.23 [[micro]meter], and with a stripe height of 0.75 [[micro]meter]. It had a corrosion resistant exchange pinning layer, [Co.sub.90][Fe.sub.10]/FeMnRh, that provided an exchange bias of 225 Oe. It produces a very stable signal and a normalized amplitude of 1 mv/[[micro]meter]/(memu/[cm.sup.2]). Furthermore its asymmetry is lower that 6%. The [Delta]R/R of the spin valve film was 5.2% with the following structure:Ta(5nm)/NiFe(2nm)/[Co.sub.90][Fe.sub.10](5nm)/Cu(2.8nm) /[Co.sub.90][Fe.sub.10](1 .2nm)/NiFe(2nm)/FeMnRh(10nm)/Ta(5nm). The spin valve heads were soaked for 96 hours in a corrosion test chamber that was operated at a temperature of 85 C and a humidity of 85%. The sensor element, the exchange bias film, the hard magnetic longitudinal bias, and the conducting leads were free from corrosion after the corrosion test. Furthermore the spin valve read-only heads were electro-migration tested in an oven operated at 120 [degrees] C, and the heads survived with the operating current up to 9 ma.

We have successfully demonstrated longitudinal recording at areal densities greater than 60 Gb/[in.sup.2] at data rates as high as 160 Mbps (20 MB/s) and at a Bit-Aspect-Ratio (BAR) of 5.7, using merged inductive-write/spin-valve-read heads with microactuators on low noise thin film disks. The heads were fabricated with the standard photolithography and wafer pole trimming used in currently available commercial products. At track densities of 60 KTPI and higher, traditional serving mechanism will not be adequate. With the use of a microactuator, we can further improve the track density by 15%, the linear density by 10% and the areal density by more than 20%. Thus, using microactuator with the 50 Gb/[in.sup.2] head/media combination we have increased our areal density achievement up to 63.2 Gb/[in.sup.2]. Index Terms--Magnetic devices, magnetic disk recording, magnetic films, magnetic heads.

Magnetic field sensitivity of IrMn-based synthetically pinned dual spin valve structures was studied using quasi-static testing (QST). The dual synthetic spin valve structure was demonstrated to have inherent advantages in terms of high sensitivity to magnetic field and robust low asymmetry against changing bias current and elevated temperatures. In addition, the diamond like carbon coated devices demonstrate that there are no measurable changes in either resistance or QST amplitude after 3 days annealing at 120 degree C. Index Terms--GMR heads, Dual spin valve heads, Synthetic antiferromegnetic-pinned spin valve, Thermal stability.

High area density magnetic recording heads with Giant-MagnetoResistance (GMR) read sensors and Focus-Ion-Beam (FIB) trimmed inductive writers were studied with a special Magnetic Force Microscope (MFM). The MFM was equipped with a Magnetoresistance Sensitivity Mapping (MSM) component that directly measures the magnetoresistance of the reader sensor as a function of position, and a High Frequency MFM (HFMFM) capability that maps 3D high frequency writing field distribution. Good agreement between the MSM measurement and the spin stand tests were obtained. MFM measurement offers unique high spatial resolutions not readily achievable with any other measurement techniques. It is the ideal tool for current and future high area density heads Index Terms--magnetoresistance sensitivity mapping (MSM); high frequency magnetic Force microscope (HFMFM); GMR recording head

We have observed a 30% of enhancement in coercivity, [H.sub.c], or a 40% increase in remnant magnetization in ion beam deposited (IBD) Cr/CoPt films as compared to IBD Cr/CoCrPt films. In addition, the magnetic properties of these hard bias films exhibit a strong dependence of on substrate and underlayer. Higher coercivity values associated with enhanced hcp Co (10??0) crystallographic orientation were measured in films grown on substrates in the preference order of glass, Si/[Al.sub.2][O.sub.3] and Si. CoPt films grown on CrV underlayer show lower [H.sub.2] values than films deposited on Cr underlayer. [H.sub.c] exhibits a maximum with increasing Cr underlayer thickness for both Cr/CoPt and Cr/CoCrPt films. This Cr thickness dependence of [H.sub.2] is correlated well with that of Co (10??0)/(0002) x-ray diffraction peak intensity ratio, indicating the role of crystallographic texture in control of coercivity of IBD hard bias films. Index Terms--IBD, Hard bias film, Microstructure, MR recording head.

We have successfully demonstrated recording at areal densities as high as 14.5 Gb/[in.sup.2] at data rates as high as 195 Mbit/s (24.4 MB/s) and at Bit-Aspect-Ratios (BAR) as high as 14, using merged inductive-write/spin-valve-read heads on low noise thin film disks. Recording at a data rate of 300 Mbit/s (37.5 MB/s) has also been achieved at the corresponding linear density of 356 KBPI. Combining the areal density and data rate capabilities, the feasibility of recording at the capacity of 15.6 GB per 3.5' platter rotating at 5400 RPM, with the average data rate of about 240 Mbit/s (30 MB/s), has thus been demonstrated. Index Terms--Areal density, data rate, media noise and spin-valve.

Demonstrates recording at areal densities as high as 14 Gb/in... at date rates as high as 195 Mbits/s and at Bit-Aspect-Ratios (BAR) as high as 14 using merged inductive-write/spin-valve-heads on low noise thin film disks. Information on high areal densities; Components of the merged heads used in the study; Parametric data of selected heads.