The magnetic and structural properties of Fe films deposited by ion-beam sputtering (IBS) on (100)-oriented GaAs substrates are described. The films are between 30 and 600 nm thick and are characterized by a coercive field of approximately 3–6 Oe. The saturation magnetization and anisotropy field, inferred from vibrating sample magnetometer measurements agree substantially with the values expected for bulk Fe. Films deposited on the (100) substrate show the expected fourfold (or ‘‘biaxial’’) symmetry with no indication of a uniaxial anisotropy component. These properties make the films ideally suitable for the intended application in a hybrid semiconductor-magnetic memory, in which two magnetic remanent states with mutually orthogonal magnetization directions interact with an electronic flip-flop circuit.

Polystyrene was photopolymerized by bulk, free-radical methods in a three-step synthesis to yield a sample containing a portion of deuterated chains at a specific conversion of interest. The initial portion of protonated polystyrene, fraction I, was cross-linked with 1 mol % divinylbenzene and polymerized up to conversions of 40-50%. The unreacted monomer was replaced with deuterated styrene monomer, and fraction II was polymerized for an additional 4-20% conversion. Fraction III was again protonated, which brought the total conversion to 100%. Fractions II and III were either linear or cross-linked. All of the compositions with fraction II greater than 4 wt % were found to have unusually high molecular weights and radii of gyration when studied by small-angle neutron scattering (SANS). SANS gave weight-average molecular weights between 110000 and 760000 for fraction II, while GPC indicated molecular weights from 110000 to 240000, yielding an apparent enhancement of SANS molecular weight of up to 5 times the GPC value. The enhancement was thought to be caused by the presence of "excluded volume" arising from previously inhomogeneously polymerized cross-linked fraction I and leads to a model suggesting a nonrandom distribution of labeled polymer, which results in several chains scattering like one large chain.

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