The coercive forces and the magnetic domains of thick permalloy films which were prepared by evaporation under different conditions such as substrate temperature, vacuum pressure and substrate materials have been studied. B-H loops, magneto-optical Kerr method, Bitter pattern observations and the internal stresses of the films were measured. The value of the coercive force and the magnetic domain of the permalloy films could be explained by the magnitude of the internal stress. Moreover, layered films which consist of a uniaxial anisotropic layer and a stripe domain layer have been found.
A trial gravimetric hygrometer has been designed and manufactured which can determine the mixing ratio of moist air (mass of water/mass of dry air) by absolute measurement. The structure of the apparatus, the operational procedure and the calibration of measuring instru-ments which compose the hygrometer are described. The source of error and the method of correction are discussed and the precision of the hygrometer is estimated to be about 10-3. The principal features of this hygrometer are as follows; (1) A 4-way valve is used for sam-pling. (2) A bypass attached to the U-tubes of the water absorber lets dry air flow directly into the parts following the apparatus before and after measurement. (3) A sonic nozzle controls the flow rate of the sample. (4) The operation can be automatized by a computer.
Electrical properties of submicron-gate (channel) self-aligned GaAs FETs having practical donor densities have been studied by two-dimensional Monte Carlo particle simulation. Dependence on the channel length, lattice temperature and donor density of the FET performance is discussed. Also, the effect of the substrate on the performance and a comparison with a submicron Si MESFET are reported.