SU1295348A1 - Device for determining period of strip domain structure in magnetic films - Google Patents

Abstract

The invention relates to computing and can be used in the manufacture of storage devices on cylindrical magnetic domains. The aim of the invention is to expand the field of application of the device by increasing the range of measured periods of the strip domain structures. A device for determining the period of a strip domain structure in magnetic films contains optically coupled light source 1, a polarizer 2, a polarization modulator 3, a sample holder 4 for a magnetic film sample 5, an analyzer 6, a photodetector 7, a phase detector 8, an alternating voltage generator 9 , linear displacement transducer Ø into a proportional electrical signal, visualization unit 1I. Moreover, the generator 9 is connected to the control inputs of the modulator 3 and the phase detector 8, the output of which is connected to the input Y of the imaging unit 11, to the input X of which the output of the converter 10 is connected mechanically to the holder 4, which is movable with a constant speed in a plane perpendicular to the overall optical axis of the device. 2 Il. to (L t45 CO SL CO CO 4 OO

Description

ig. one

0

15

112953А8

The invention relates to computing and can be used in the manufacture of storage devices on cylindrical magnetic domains (CMD).

The purpose of the invention is to expand the field of application of the device by increasing the range of values of the measured periods of the strip domain structures.

Figure 1 shows the block diagram of the proposed device; FIG. 2 is a diagram of the output signal on the screen (chart tape) of a visualization unit.

A device for determining the period of a strip domain structure in magnetic films contains optically coupled light source 1, a polarizer 2, a polarization modulator 3, a sample holder 4 for a magnetic film sample 5, an analyzer 6, a photodetector 7, a phase detector 8, an alternating voltage generator 9 , a linear displacement transducer 10 into a proportional electrical signal, a Visualization unit 11, the generator 9 being connected to the control inputs of the modulator 3 and the phase detector 8, the output of the detector B being connected to the input-. dU Y of visualization unit 11, quhoX of which is connected to the output of transducer 10, mechanically connected with holder 4, which is capable of moving at a constant speed in a plane perpendicular to the overall optical axis of the device.

20

25

thirty

35

The proposed device works as follows.

The sample of the studied magnetic film 5 is placed on the holder 4, moving at a constant speed in a plane perpendicular to the overall optical axis of the device, along which the light beam propagates from the light source 1, the polarizer 2 passing successively, the modulator 3, launched from the generator 9, the film sample 5, the analyzer 6, is mounted crosswise with the polarizer 2, and reaching the photodetector 7. The movement of the holder 4 is carried out from the microtransmitter (not shown) and is based on the thermal expansion of the metal pin (magnetostriction can also be applied

0

five

3А8

0

2

onion, piezoelectric and similar microdisplacement mechanisms). In this case, sample 5 is oriented so that the direction of movement is perpendicular to the boundaries of the strip domains previously formed in the sample 5 of the film using a planar alternating magnetic field with a decreasing amplitude to achieve an equilibrium state of the domains. In the path of the light beam, a diaphragm (not shown) is set so that a light signal from only one domain arrives at the photodetector 7. The amplitude of the polarization modulation with the help of the modulator 3 and the generator 9 is chosen to be close (but not exceeding) to the value of the Faraday rotation of the polarization plane associated with the interaction-5

0

five

five

five

0

light beam with magnetic film domains. The signal from the photodetector 7 is fed to the input of the phase detector 8 controlled from the generator 9, and from the output of the detector 8 the signal is fed to the input Y of the visualization unit 1I,. When a domain with a positive magnetization enters the path of the light beam, the signal at the output of the detector 8 and, respectively, at the input Y of the visualization unit P is maximum (determined by the conversion coefficient of the photodetector and the gain of the measuring circuit) when the domain of the signal opposite the magnetization of the input signal Y unit 11 visualization is minimal (at the level of the noise of the measuring circuit). The magnitude of the movement of the holder 4 and with it the sample 5 of the film by means of the converter 10 is transformed into a proportional electrical signal, which is fed to the input X of the visualization unit 11. As a result, a periodic curve (Fig. 2) is recorded on the screen (chart tape) of the visibility block 1 1. The maxima of the curve correspond to the passage of the light beam over the middle of the domains with a positive magnetization, the minima - to domains with a negative magnetization. At the same time, a value is plotted along the X axis, which is proportional to the movement of the film sample 5 with the holder 4 moving uniformly. The coefficient of proportionality C between the non-personal X on the diagram and the true movement of the film sample is determined previously with an object micrometer or test scale with a known distance between strokes. The desired period of the bandwidth of the domain structure P is determined. Through the period of the Xp curve in the diagram (FIG. 2), taking into account the proportionality coefficient: PJ,, As a test of scales, opaque parallel strokes applied on a transparent substrate and equal to the distance between the strokes are used , and with a period close to the period of the studied band domains. Such tests imitate the structure of the band domains well, but differ from the latter in greater (almost 100%) contrast .. therefore they are easily distinguishable in any size, including submicron, both visually and on the chart of the visualization unit of the proposed device.

Claims (1)

Formula of gain A device for determining the period, the strip domain structure in magnetic films, containing an optically coupled light source, a polarizer, an analyzer and a photodetector, holding five 0 five 0 The sample of the magnetic film, located between the polarizer and the analyzer, is different from the fact that, in order to expand the field of application of the device by increasing the range of values of the measured periods of the strip domain structures, it contains a polarization modulator located on the common optical the axis of the device between the polarizer and the sample holder of the magnetic film, an alternating voltage generator, a phase detector, a visualization unit, a linear displacement transducer into an electrical signal, The ac voltage generator is connected to the control inputs of the polarization modulator and the phase detector, the output of the photodetector is connected to the input of the phase detector, the output of which is connected to one of the inputs of the imaging unit; to the other input of which the output of the linear displacement transducer into an electrical signal is connected associated with the holder of the sample of the magnetic film, which is designed to move at a constant speed in a plane perpendicular to the overall optical axis of the device. Editor 0, Bugir Compiled by Yu, Rosenthal Tehred I. Popovich Order 614/53 Circulation 731 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Proektna st, 4 Proofreader M.Sharoshi