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CoPt and CoPt/Au films prepared by magnetron sputtering were studied in this paper. The films were deposited at room temperature followed by a post annealing at temperatures ([T.sub.a]) from 400[degrees]C to 800[degrees]C. Ordering of the CoPt and CoPt/Au films occurred at [T.sub.a] = 600[degrees]C and 500[degrees]C, respectively, which results in magnetic hardening. With the increase of [T.sub.a] up to 700[degrees]C, coercivity of the both films increased to a maximum value of about 12 kOe. As [T.sub.a] reached 800[degrees] C, a drastic magnetic softening occurs in both samples; meanwhile, the diffraction data indicate a corresponding phase change from tetragonal to cubic. Scanning electron microscopy results revealed an intensive grain growth from 70 nm at 700[degrees]C to 160 nm at 800[degrees]C for CoPt/glass film and from 110 nm at 700[degrees]C to 250 nm at 800[degrees]C for CoPf/Au/glass sample. The relation between the abnormal phase change and intensive grain growth indicates that the formation of the cubic phase is driven by large biaxial tensile stress. Further investigations support this explanation and reveal that the cubic phase may be chemically ordered. Index Terms--CoPt, magnetic softening, phase transformation, thin films.

[Fe.sub.53][Pt.sub.47] and [Fe.sub.58][Pt.sub.42] thin films with 300 nm in thickness prepared using magnetron sputtering were investigated. The films were deposited on heated glass substrates and annealed at 400[degrees]C and 800[degrees]C for different time. Single phase FePt films with similar chemical ordering but different substructure size were produced in the two series of samples. The effect of microstructure refinement results in significant enhancement in remanence ([M.sub.r]) of about 38.1% and 30.8% in the [Fe.sub.53][Pt.sub.47] and [Fe.sub.58][Pt.sub.42] films, respectively. The energy product, [(BH).sub.max], also showed a large increase of 25% and 72%; the maximum value of the two series of films are 16.2 MGOe and 19.6 MGOe, respectively. The large [(BH).sub.max] was found to originate from the enhancement of [M.sub.r] and steep slope of demagnetization curve at coercive point ([alpha]). As the theoretical predictions, in an isotropic magnet, the magnetic moments in the transition region of magnetization near grain boundary are easy to be aligned by applied field. In this study, it is found that by increasing the magnetic transition region through microstructure refining, the remanence can be effectively enhanced meanwhile facilitate the collective magnetic reversal. Domain structure confirms that the refinement of microstructure effectively reduces the domain size. Index Terms--Energy product, exchange coupling, FePt, microstructure refinement, reversible magnetization.

[Fe.sub.100-x] [Pt.sub.x] (x = 20, 25, and 30) thin films with nominal thickness 50 nm were prepared by radio-frequency (RF) magnetron sputtering onto glass substrates. Crystallographic structure and magnetic properties of such films were investigated by varying Fe content, annealing temperature (400-700 [degrees]C), and heating process. Crystallographic structure obtained by X-ray diffraction (XRD) indicated that ordering of [L.sub.12] [Fe.sub.3] Pt phase takes place for [Fe.sub.75] [Pt.sub.25] postannealed above 400 [degrees]C. Ordering parameter of the [Fe.sub.75] [Pt.sub.25] sample increases from 0.29 to 0.94 as annealing temperature rises from 400 [degrees]C to 700 [degrees] C. Saturation magnetization 1270 emu/[cm.sup.3] was obtained in [Fe.sub.75] [Pt.sub.25] films annealed at 700 [degrees]C. [Fe.sub.70] [Pt.sub.30] films annealed at 700 [degrees]C show similar characteristics with those of [Fe.sub.75] [Pt.sub.25], while [Fe.sub.80] [Pt.sub.20] films exhibit paramagnetism due to disordered Fe-rich face-centered cubic (fcc) structure. Postannealing seems necessary for formation of pure [L1.sub.2] [Fe.sub.3] Pt phase while in situ annealing leads to formation of a metastable tetragonal [Fe.sub.3] Pt phase, as confirmed by XRD. Index Terms--Coercivity, [Fe.sub.3] Pt thin films, [L1.sub.2] superlattice, metastable phase, phase transformation, saturation magnetization.

A fully conjugated blood vessel network model (FCBVNM) for calculating tissue temperatures has been developed, tested, and studied. This type of model represents a more fundamental approach to modeling temperatures in tissues than do the generally used approximate equations such as the Pennes' BHTE or effective thermal conductivity equations. As such, this type of model can be used to study many important questions at a more basic level. For example, in the particular hyperthermia application studied herein, a simple vessel network model predicts that the role of counter current veins is minimal and that their presence does not significantly affect the tissue temperature profiles: the arteries, however, removed a significant fraction of the power deposited in the tissue. These more fundamental models can also be used to check the validity of approximate equations. For example, using the present simple model, when the temperatures calculated by the FCBVNM are used for comparing predictions from two approximation equations (a simple effective thermal conductivity and a simple Pennes' bio-heat transfer equation formulation of the same problem) it is found that the Pennes' equation better approximates the FCBVNM temperatures than does the [k.sub.eff] model. These results also show that the 'perfusion' value (W) in the Pennes' BHTE is not necessarily equal to the 'true' tissue perfusion (P) as calculated from mass flow rate considerations, but can be greater than, equal to, or less than that value depending on (1) how many vessel levels are modeled by the BHTE, and (2) the 'true' tissue perfusion magnitude. This study uses a simple, generic vessel network model to demonstrate the potential usefulness of such fully conjugated vessel network models, and the associated need for developing and applying more complicated and realistic vascular network models. As more realistic vascular models (vessel sizes, orientations, and flow rates) are developed, the predictions of the fully conjugated models should more closely model and approach the true tissue temperature distributions, thus making these fully conjugated models more accurate and valuable tools for studying tissue heat transfer processes.

The heat transfer within a perfused tissue in the presence of a vessel is considered. The bio-heat transfer equation is used for the perfused tissue and a lumped capacitance analysis is used for the convection in the vessel with a constant Nusselt number. Analytical solutions are obtained for two cases: (i) the arterial temperature of the perfused blood in the bio-heat transfer equation is equal to the axially varying mixed mean temperature of the blood in the vessel and, (ii) that arterial temperature is assumed to be constant. Dimensionless equilibrium length and temperature expressions are obtained and presented.

Effect of Ag segregation on magnetic and structural properties of [(FePt).sub.77] [Ag.sub.23] single-layer films were studied. Thin films were first sputtered on the heated glass substrates and cooled to room temperature, a post annealing at temperatures ([T.sub.p]) from 200 [degrees]C to 400 [degrees]C for 60 min was then applied. [L1.sub.0] structure formed as substrate temperature ([T.sub.s]) equals to 600 [degrees]C and 700 [degrees]C. For those ordered films, Ag was observed to precipitate as particles on the film surface and grow with the increasing [T.sub.s]. After post annealing at 400 [degrees]C for 60 min, those silver particles dissolved into the film, leading to changes in reversal behavior. The optimum condition is obtained in the [T.sub.s] = 600 [degrees]C, [T.sub.p] = 400 [degrees]C sample. Drastic reduction in coercive squareness ratio (from >0.8 to 0.41) and enhanced coercivity (from 4.7 to 6.4 kOe) indicate the reversal behavior alters from cooperative to independent. Negative [delta]M curve suggests that this independent rotation results from the reduction of exchange interactions. Index Terms--Coercivity enhancement, domain structure, FePt, reversal behavior, segregation, thin film.

Single-layer FePt, bilayer Mo/FePt and FePt/Mo, and trilayer Mo/FePt/Mo samples were prepared by rf magnetron sputtering. Each layer of FePt and Mo in the studied samples is 20 nm in thickness. Samples were deposited onto corning 1737 glass substrate at room temperature, then annealed at 350[degrees]C and 400[degrees]C for a period of 10-120 min. Coercivities of the Mo-layer introduced samples were higher than those of single-layer FePt. X-ray diffraction data also indicate higher degree of ordering for Mo-layer introduced samples. We suggest that the incoherent FePt/Mo interface may induce extra nucleation sites for ordering transformation, thus lower the threshold of ordering temperature. Index Terms--Coercivity enhancement, FePt/Mo bilayer films, FePt/Mo interface, ordering enhancement.

In this paper, the effect of disjoining pressure was investigated for its role in lubricant transfer from magnetic recording disks to heads. The disjoining pressure was calculated from contact angle measurements on disks. The amount of lubricant transfer was measured with a slow seek test on a spin stand. The results showed that the amount of lubricant transfer is reduced as the disjoining pressure becomes more positive and the slope of the disjoining pressure--lubricant thickness curve more negative. Also, the disjoining pressure takes several weeks to stabilize, depending on the carbon-lubricant system. However, stabilization can be accelerated with a thermal or UV treatment. Index Terms--Disjoining pressure, disk drives, lubrication.

The effect of microstructure refinement on magnetic properties in single-phase [L1.sub.0] [Fe.sub.58][Pt.sub.42] films is examined. The results have shown a decrease of ordering near the phase boundaries within the thickness range of about 1 nm and this structural transition region has reduced magnetocrystalline anisotropy, thus resulting in an increase of remanence.