This paper describes the performance of a scanning nonlinear dielectric microscope when a gap exists between the specimen and the probe of the microscope. First, a theory for the sensitivity of the scanning nonlinear dielectric microscope as a function of the gap height is described. Second, using the microscope in a noncontact mode, an area scan of the polarization of an alternately poled ferroelectric thin film of a copolymer consisting of vinylidene fluoride and trifluoroethylene is carried out.
This paper describes a new technique for imaging the distribution of nonlinear dielectric constants of ferroelectric materials. This technique is based on the principle that the nonlinear (third-order) dielectric constants (third-rank tensor) are very sensitive to the state of the spontaneous polarization and the quality of the crystallization of materials, while the linear (second-order) dielectric constants (second-rank tensor) are insensitive to them. Applying this principle, a new microscope for measuring the distribution of nonlinear dielectric properties is developed. This new microscope is used to observe the distribution of the polarization of ferroelectric materials such as lead zirconate titanate (PZT) ceramic and piezoelectric polymer.
Although there have been various theories on the effect of the magnetic saturation of a write head on the recording characteristics of a magnetic medium, they include many vague points. to obtain a complete picture of the effects, this paper compares the digital recording characteristics. These have been obtained by changing the starting point of the saturation of a write head over a wide range referring to the saturation point of a magnetic medium (the variation is made utilizing the temperature characteristics of ferrite used for the head). When the head is not saturated, in both the unsaturated region and the highly saturated region of the medium, the recording characteristics of the medium depend greatly on the recording magnetic field strength. This dependency is less in the region between the two regions. In the two regions, if the head is saturated, the variation of the write characteristics due to the write current is restrained after saturation. In the intermediate region, if the pole tip is saturated, the write characteristic is somewhat degraded. If the head is saturated around the intermediate region, the overwrite erase rate is greatly degraded, since this is sensitive to the erase magnetic field strength around the saturation point of the medium.
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