SU1755220A1 - Method of non-destructive measuring of saturation magnetization and anisotropy constant of ferromagnetic films - Google Patents

Abstract

The invention relates to electronics and electronics and can be used in measuring the parameters of ferromagnetic films in the process of their production, and in the manufacture of film spin-wave microwave devices. The essence of the method is that the spin waves excite a microwave alternating magnetic field simultaneously in two regions of the ferromagnetic film under study and at each orientation of the constant magnetic field the frequencies of the spin waves corresponding to the minima of the frequency dependence of the microwave power reflected from the sample under investigation are measured. film parameters are determined by measured frequency values using dispersion ratios. 2 Il.

Description

The invention relates to electronics and electronics and can be used in measuring the magnetic parameters of ferromagnetic films (for example, saturation magnetization, anisotropy constants) both in the process of their production and in the manufacture of spin-wave film microwave devices.

The aim of the invention is to improve the measurement accuracy.

Figure 1 shows the structure of a device implementing a method for measuring parameters of ferromagnetic films; figure 2 - frequency dependence of the power of the reflected microwave signal.

The measuring installation consists of a magnetic system 1. measuring section 2. UHF generator 3, directional 4, detector 5, indicator 6. Measuring section 2 (Fig. 1b) is an antenna system consisting of a dielectric substrate, solid a metal electrode 8, a microstrip line 9, two microstrip antennas 10, which are parallel to each other at a distance I, measured by a ferromagnetic film 11, located on a dielectric substrate 12. Microstrip line 9 connects to the measuring first installation through sverhvysokochastotiy coaxial cable 13.

The sequence of actions for measuring the saturation magnetization and anisotropy constants of a ferromagnetic film is as follows.

A measuring section is assembled that consists of a ferromagnetic film of yttrium iron garnet (YIG) of thickness L grown on a dielectric substrate of gadolinium gallium garnet (YYY) ferromagnetic film superimposed on an antenna system consisting of two parallel microstrip antennas width W located on

fc

listened to u

Yu

distance I. The measuring section is placed in a magnetic system that creates a constant magnetic field with an intensity But directed along the axis of the antennas of the spin waves. In this case, the mode of excitation of a surface spin wave is realized. Using a microwave generator, the frequency dependences of the reflected power of the microwave signal Rothf (ft) npii of two different directions of the magnetic field But are measured relative to the crystallographic axes of the film, which is realized by rotating the film relative to the field H0. As can be seen from figure 2, the dependence of Rotr. f (co) has an oscillating pattern, and the wave number values at the minima of the P0tp f (s) dependencies are determined at A $ 012 0 from a simple relation:

kn - 2f. (D

where p is the angle of orientation of the periodicity axis of the magnetic field relative to the direction of propagation of the spin wave;

I is the distance between microstrip antennas.

When the film is rotated, the minima of the P0TP f (w) dependence shift due to the effect of cubic anisotropy. Curve 1 in figure 2 corresponds to the orientation of the field But along, curve 2 - orientation of the field But along the axis 110.

The frequencies corresponding to any nth minimum in the Potr dependence f (ft) are measured first with orientation of the magnetic field H0 along the crystallographic axis 110 (soi110), and then with the orientation of Ho along the crystallographic axis 112 (ohm). The values are determined.

TO

Moe

well, the floor of cubic anisotropy H using the ratio:

UA. .1-lt ,. fr, i 110l2i1 / 2 / o

U ST

where KA is the constant of cubic anisotropy;

Mo - magnetization;

j 2.28 MHz / E is the magnetomechanical ratio.

So, when determining H from any peak of dependencies Rotor f (SU), presented in figure 2, we get the NA -56E.

Frequency values corresponding to three minima (arbitrary, with nn and n numbers) are measured on the frequency dependence of Rotr f (w) with the H0 field oriented along the axis 112 and the magnetization value M0 and the uniaxial anisotropy field Ni KI / M0 are determined (Ki - uniaxial anisotropy constant) using ratios:

Mo l () (P-PR,) - (av: i-tUh.2) (pn, -Pg) W

XI1M-Рп К J (IV- Р „) L,

 I ".i.Me (p. + Pl,)

12m0 (p; -rp)

(h)

NO Mo-NA (O

where Pn is a polynomial depending on kn — the wavenumber of spin waves.

In the long-wavelength approximation (kn I), Pn is determined using the ratio

p - - L (5)

Hn - jP2-

The values of M0, NA, and Ni can be determined using expressions (2) - (4) by measuring the frequencies corresponding to any minima on the Rotor dependence f (ft), which makes it possible to determine the averaged values of the parameters M0, KA, Ki for a greater number of experimental points on addiction

Roth f I.

Claims (1)

The method of non-destructive measurement of saturation magnetization and anisotropy constants of ferromagnetic films, including simultaneous exposure of a constant magnetic field and a microwave magnetic field to a film, changing the direction of a constant magnetic field relative to the crystallographic axes of the film and determining the parameters of the film from the dispersion relation, differing from the fact that, in order to increase the measurement accuracy, two parallel regions of the film are applied to the constant and microwave E field E, depending on the frequency of the reflected microwave power at each orientation of the static magnetic field is fixed points corresponding to the minimum value of the power. i FIG. La den  "Y. and no about 4 $ 00 4950 xy NAyjKi a mcnuQQQOQOp (gsS 10, 10 eight $ 000 $ 050