CN1027200C

CN1027200C - Manganese bismuth adding rare-earth element magneto-optical film medium

Info

Publication number: CN1027200C
Application number: CN 90110030
Authority: CN
Inventors: 方瑞宜; 李东镭; 刘明升; 杨丹坤; 戴道生
Original assignee: Peking University
Current assignee: Peking University
Priority date: 1990-12-28
Filing date: 1990-12-28
Publication date: 1994-12-28
Anticipated expiration: 2005-12-28
Also published as: CN1062805A

Abstract

The present invention relates to a Manganese Bismuth adding rare earth element magneto optical film medium. Light rare earth elements R (R represents La, Ce, Pr, Nd, Sm and Gd) are added in MnBi. The present invention has the advantages that the formula of charging during vapor deposition, so the thermal stability of the medium is improved, a magneto optical Kerr rotation angle theta-[K] (theta-[K] is equal to 1.8-2.6 DEG) is greatly increased, and the value of a magneto-optical optimum value theta-[K] R-[K] of the medium is increased. The present invention adopts the method that base sheets are cooled by liquid nitrogen during the vapor deposition, the generated crystal particles are fined, and noises of crystal boundaries is reduced. The present invention adopts a stepping annealing method in an annealing technology, so the property uniformity of samples is improved; the present invention is used for media of a magneto optical disk in a magneto optical memory technique and metallic film media of various magnetic optical devices in the magneto optical technique.

Description

Manganese bismuth adding rare-earth element magneto-optical film medium

The invention belongs to physics magneto-optic memory technique class, it is the metallic film medium that is used as the medium of magneto-optical disc in the magnetooptical memory technique and is used as the various magnetic-optic devicess in the magneto-optic technology.Materials similar has MnBiAlSi and MnBi to add the transition alloy firm with it.The maximum magneto-optic Kerr rotational angle theta delivered of MnBiAlSi film for example _K=2.0 °.

Fundamental purpose of the present invention is further to improve the magneto-optic volt value θ of medium _K

\sqrt{R}

_Instead(R _InsteadReflection coefficient for medium).

Main technical points of the present invention is to prepare on the basis of MnBi film in traditional vacuum evaporation, adds light rare earth element R(R=La, Ce, Pr, Nd, Sm, Gd), and adopt the method for cooling substrate and suitable Technology for Heating Processing, make a series of novel MnBiR films.Its Heat stability is good, crystal grain is thin, θ _KGreatly, R _InsteadModerate, this film can be used as the medium of magneto-optical disc in the magnetooptical memory technique and the thin film dielectrics of various magnetic-optic devicess.

Particular content of the present invention and scheme

1. composition

The atomic ratio that feeds intake during the system film is Mn/Bi=1.5-3.5, and the amount of the light rare earth element R of interpolation is R/Bi=0-0.4.

2. preparation method

The raw material of Mn, Bi and R is put into crucible respectively, and (vacuum tightness is 10 with vacuum evaporation ^-6Torr) method, evaporation are to glass substrate, and substrate covers SiOx as protective seam again with cooled with liquid nitrogen (temperature at-196 ℃ to adjustable between the room temperature), and (vacuum tightness was 10 in 3-5 hour 300-420 ℃ vacuum furnace annealing then ^-5-10 ^-6Torr).The sample that has has adopted the annealing process of " step-by-step movement ", and annealing is 1-2 hour under said temperature.MnBiR film with above-mentioned technology preparation is the mixed-crystal structure of MnBi+MnBiR.See X-ray diffract spectral line among Fig. 1.

The advantage of the film that the present invention makes and effect

1. pure MnBi film has phase transformation to occur near 350 ℃, makes the poor heat stability of medium, can't be practical.After adding the R element, this phase transformation do not occur, improved the thermal stability of medium.

With the crystallite dimension of the pure MnBi film of conventional method preparation at several micrometer ranges, make the crystal boundary noise of medium very big, can't be practical.The crystallite dimension of the MnBiR film for preparing with the method for cooled with liquid nitrogen substrate when adding light rare earth element R and evaporation reduces crystal grain greatly, thereby has reduced the crystal boundary noise less than 50 nanometers (seeing Fig. 2 photo).

3. with the θ of the film of the present invention preparation _KVery big (θ _K≈ 1.8-2.6 °), and reflection R _InsteadModerate, R _Instead≈ 0.3-0.45 is shown in Fig. 3 and 4.

4. the magnetic hysteresis loop by the MnBiR film shows, squareness ratio is generally all more than 0.9, and has well vertical face uniaxial anisotropy, sees Fig. 5 and 6.

5. by mixing rare earth and appropriate heat treatment, the coercivity H of film can be controlled at 2KOe between the 5KOe

6. the saturation magnetization σ of film _SAt 20-50emu/g, Curie point Tc is at 340-360 ℃.

In a word, because the θ of medium _KVery big, R _InsteadSuitably, can obtain very big magneto-optic volt value θ _K

\sqrt{R}

_InsteadIt is in the world about five times of the volt value of practical magnet-optical medium at present, and is all bigger than the result who reports in the domestic and international existing document.The θ of MnBiAlSi medium for example _KMaximal value θ _K=2.0 °, the θ of PtMnSb _K=1.2-1.8 °.Therefore, it is hitherto known θ _KMaximum individual layer magneto-optical film medium.Also because its Heat stability is good, crystal grain is thin, is applicable to the magneto-optical disc medium done in the magnetooptical memory technique and the material of magneto-optic modulator spare.

Embodiment:

Adopt particular content and the described prescription of scheme and the technology of the invention described above, (40 * 13mm), its performance has reached the result shown in Fig. 1-6 to the little print of having made.Its specific practice is illustrated the composition and the performance thereof of sample below in conjunction with accompanying drawing:

The X-ray diffract spectral line of Fig. 1 MnBiNd magneto-optic thin film is that rate of charge is that Mn: Bi: Ce is the MnBiNd that made in 3.4: 1.0: 0.33 o'clock.

Fig. 2 is to be that Mn: Bi: Ce is the pattern photo of the MnBiCe magneto-optic thin film made in 2.08: 1.0: 0.12 o'clock at rate of charge.

(take with transmission electron microscope, each centimetre represented 1000A ° of size).

Fig. 3 is that a kind of rate of charge is that Mn: Bi: Ce is the Keer rotational angle theta of the MnBiCe magneto-optic thin film made in 2.08: 1.0: 0.2 o'clock _KWith reflectivity R _InsteadRelation curve with optical wavelength; Because the θ of medium _KVery big, R _InsteadSuitably, can obtain strengthening the volt value of five times magnet-optical medium, be current known θ _KPeaked individual layer magneto-optical film medium.

The θ of Fig. 4 magneto-optical film medium _KWith its concrete composition of optical wavelength relation curve note in the drawings.

Fig. 5 is that a kind of rate of charge is that Mn: Bi: Nd is the magnetic hysteresis loop of the vertical and parallel face of the MnBiNd magneto-optical film medium made in 2.06: 1: 0.4 o'clock.

Fig. 6 is that a kind of rate of charge is that Mn: Bi: Ce is the vertical face torque deltoid of the MnBiCe magneto-optical film medium made in 2.08: 1.0: 0.10 o'clock.

Composition by above sample is implemented, and resulting magneto-optical film medium has Heat stability is good, and the crystal boundary noise is little, and the volt of magnet-optical medium is rolled (θ _K) performance such as maximum reaches the adjacent first level in the world.

Description of drawings:

The X-ray diffract spectral line of Fig. 1 MnBiNd magneto-optic thin film

Be that rate of charge is that Mn: Bi: Ce is 3.4: 1.0:

0.33 the time MnBiNd that makes

The pattern photo of Fig. 2 MnBiNd magneto-optic thin film

Be to be that Mn: Bi: Ce is 2.08: 1.0 at rate of charge

: the shape of the MnBiCe magneto-optic thin film of making in 0.12 o'clock

The looks photo

The θ of Fig. 3 MnBiCe magneto-optic thin film _KAnd R _InsteadWith wavelength relationship

Be that a kind of rate of charge is that Mn: Bi: Ce is 2.08:

1.0: the MnBiCe magneto-optic thin film of making in 0.2 o'clock

The Keer rotational angle theta _KWith reflectivity R _InsteadWith optical wavelength

Relation curve; Because the θ of medium _KVery big, R _InsteadSuitable

When, can obtain strengthening the volt of five times magnet-optical medium

Value is current known θ _KPeaked individual layer

Magneto-optical film medium

The θ of four kinds of MnBiR magneto-optic thin films of Fig. 4 _KWith the wavelength relationship song

Line

The θ of magneto-optical film medium _KConcern its tool with optical wavelength

The body composition is note in the drawings

Vertical and the parallel face of Fig. 5 MnBiNd magneto-optic thin film

Magnetic hysteresis loop

Be that a kind of rate of charge is that Mn: Bi: Nd is 2.06:

The MnBiNd magneto-optical film medium of making in 1: 0.4 o'clock

The magnetic hysteresis loop of vertical and parallel face

The vertical face torque shape song of Fig. 6 MnBiCe magneto-optic thin film

Line

Be that a kind of rate of charge is that Mn: Bi: Ce is 2.08:

1.0: the MnBiCe magneto-optic thin film of making in 0.10 o'clock is situated between

The vertical face torque deltoid of matter

Claims

1, a kind of manganese bismuth magneto-optical film medium is characterized in that adding light rare earth element R (R represents La, Ce, Pr, Nd, Sm and Gd), and the atomic ratio that feeds intake during its system film is:

Mn: Bi is between 1.5 to 3.5

R: Bi is between 0 to 0.4

By Mn, the magneto-optical film medium that three kinds of elements of Bi and R are made is write a Chinese character in simplified form into the MnBiR form.

2, a kind of preparation method of magneto-optical film medium of manganese bismuth adding rare-earth element is characterized in that adopting the method for cooling substrate and the temperature-rising method of " step-by-step movement ".

3, according to the preparation method of the magneto-optical film medium of claims 2 described manganese bismuth adding rare-earth elements, its cooling substrate is characterised in that:

1) substrate is close to on the copper soleplate of cooled with liquid nitrogen, and minimum temperature can reach-196 ℃, adopts temperature control method, make baseplate temp at-196 ℃ to adjustable between the room temperature;

2) covering SiOx on the magneto-optical film medium after making as protective seam, is 300-420 ℃ of vacuum furnace annealing 3-5 hour in temperature then, and vacuum tightness is 10 ^-5-10 ^-6Torr.

4, according to the preparation method of the magneto-optical film medium of claims 2 described manganese bismuth adding rare-earth elements, the temperature-rising method that it is characterized in that " step-by-step movement " is that the annealing temperature of sample is selected several temperature between 300 ℃-420 ℃, annealed successively 1-2 hour, optional 350 ℃ of annealing are after 1 hour, heat again immediately rise to 375 ℃ annealed again 1 hour after, heat again immediately to 400 ℃ of annealing 1 hour, drop to room temperature at last.