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Highly transparent Cu2O thin films on transparent conducting oxide on a glass substrate were fabricated using reactive sputtering by carefully controlling the O2 flow. The impurity dependence of transmittance was thoroughly investigated, and the transmittance was found heavily depending on impurities in Cu2O thin films as confirmed by x-ray diffraction analysis. A highly transparent Cu2O thin film was fabricated using precisely impurity-controlled Cu2O thin films. The effects of impurities in a Cu2O thin film on photovoltaic properties were studied. A maximum efficiency of 8.4% was observed in the lowest-impurity Cu2O thin film. [ABSTRACT FROM AUTHOR]

A soft-output data-detection scheme optimized for data-dependent media-noise recording channels is investigated that uses signal-dependent correlation-sensitive (SDCS) metric computation for post-processing decoding. This media-noise soft-output (MNS) decoding scheme achieves suboptimal maximum-likelihood (ML) sequence detection in a nonstationary media-noise channel, while still using traditional Viterbi detection. Because it drastically reduces SDCS metric computation by focusing on correcting only the dominant error events in the ML detector, it is less complex than other suboptimal detection schemes. Moreover, the MNS decoding scheme provides parity-check-code decoding with more reliable soft-output information. Simulation showed that MNS decoding in conjunction with a conventional M[E.sup.2]PRML system, provides an excellent tradeoff between data-detection performance and computation complexity for a jitter-noise dominant high-density recording channel. Index Terms--Maximum-likelihood (ML) sequence detection, nonstationary media noise, post-processing decoder, signal-dependent correlation-sensitive (SDCS) metric.

An exact calculation method for the medium field from a perpendicular magnetic recording medium with a soft underlayer was derived. The new method utilizes the Fourier series expansion, and the derived equation converges to the equation for the medium without a soft underlayer in the limit of infinite distance between the head surface and the soft underlayer. The new method, when combined with a micromagnetics simulation of the medium and the giant magnetoresistive head, provides a useful tool for the analysis of the read back signals in perpendicular magnetic recording. Index Terms--Field calculation, giant magnetoresistive heads, magnetic recording, perpendicular magnetic recording.

We evaluated the performance of fixed-delay tree-search detector with decision feedback (FDTS/DF) when used for nonlinear magnetoresistive (MR) read head channels. The feedback section of the FDTS/DF was replaced by RAM lookup table for nonlinear equalization. The evaluation was based on a computer simulation in which the read-back signal from the MR head was modeled from a measured MR transfer characteristic function and actual real reproduced isolated pulses. This performance was compared to that of PRML channels. We also compared the sensitivity of the FDTS/DF and PRML channels to variations in the recording channel frequency response due to head-medium spacing fluctuation. The results show that the FDTS/DF channel has good resistance to MR nonlinear distortion and channel response variations, and is superior to the PRML channels in terms of realistic recording channel response.

Linearity in perpendicular magnetic recording was studied. An asymmetrical transition-shift occurs depending on the polarity of the pre-recorded magnetization of a medium, which deteriorates linearity. A new single pole head with two main poles which we call the bi-layered head improved linearity by avoiding the interference of magnetic field from the magnetized medium with the head field. As a result, 200 kFRPI recording was demonstrated to be practical with the partial response technique.

Values for field through the read element (H read) in longitudinal and perpendicular magnetic recording are compared with the aid of three-dimensional (3d) finite element models. The H read of the single-pole-type head used in perpendicular magnetic recording (PMR) is larger than that of the inductive ring head used in longitudinal magnetic (LMR).

A new field calculation method was developed for the reading process that involves a double-layered medium with a soft underlayer. The image fields due to both the underlayer and the ABS have to be taken into consideration. It was found that the field can be expressed in an equation similar to that describing multiple reflection of light in an optical multilayer, except that the scalar terms in the optical system have to be replaced with tensor terms with Fourier components as bases. This field, in turn, may be used as an input to a micromagnetic simulation model for GMR head to give the reproduced signal. Index Terms--Field calculation, magnetic recording, perpendicular recording.

We have fabricated a new layered structure, named "U-mag," for perpendicular magnetic recording media, in terms of stacked flints including a very thin (2 nm) ferromagnetic (Co) intermediate layer and lattice spacing control layers. The formed medium having a 100-nm soft magnetic underlayer with high coercivity over 6 kOe and sufficient nucleation field (-1.5 kOe) shows higher signal-to-noise ratio (SNR) than a medium with a conventional Ru underlayer. The detailed microstructures of the U-mag medium were also revealed by a transmission electron microscope with an energy dispersive spectrometer. A double Co intermediate layer gave a significant improvement in the SNR compared to a single Co layer. [ABSTRACT FROM AUTHOR]