JPH02235285A - Method for driving magnetic storage element - Google Patents

Abstract

PURPOSE:To provide a sufficiently long moving distance to the pair of vertical Bloch lines (VBLs) to obtain a large operation margin by impressing a pulse-like bias magnetic field in the same direction as a static bias magnetic field. CONSTITUTION:A magnetic wall 13 formed on the outside of a stripe magnetic domain 12 stabilized by a static bias magnetic field 32 with polarity around a groove 11 engraved on a garnet film is used as a transfer line of VBL pairs and a local intra-face magnetic field is generated by allowing current to flow into a zigzag conductor 21 to form the stable positions 5 of the VBL pairs on the magnetic wall 13. A pair of VBLs is transferred to the succeeding stable positions 5 by impressing a pulse-like bias magnetic field 31 in the same direction as the magnetic field 32 from the external. Consequently, a sufficiently long moving distance can be applied to the VBL pair 1 and the transfer margin of the VBL pair can be sharply improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for driving a pair of vertical prosophore lines using a pulsed bias magnetic field used in a Bloch line memory.

(Prior technology) As an ultra-high-density solid-state magnetic memory element that replaces a magnetic bubble memory element, the boundaries of striped magnetic domains existing in a ferromagnetic (including ferrimagnetic) film whose easy magnetization direction is perpendicular to the film surface are formed. exists stably within the Bloch domain wall that
A Bloch line memory element was invented that uses a Bloch line pair (hereinafter referred to as a VBL pair) consisting of two vertical Bloch lines as a memory unit (Japanese Patent Application No. 1882-1982).
346).

In a Bloch line memory element, information is written in the form of VBL pairs along the Bloch domain wall around the stabilized stripe magnetic domains that constitute the minor rube, and the information is written in the form of VBL pairs.
A means for reading information units represented by a minute area called L pairs, and a means for transferring and holding VBL pairs bit by bit on a minor loop are essential.

To stabilize striped magnetic domains, a stripe fixing method by trenching is used, and to fix VBL bits on stabilized stripes, local in-plane magnetic fields generated from battened in-plane magnetized films and current conductors are used. It is common to use potential. A specific example is shown in FIG.

In Figure 3, 11 is a groove dug into the garnet layer;
12 is a striped magnetic domain that constitutes a minor rube, 13
is the Bloch domain wall around the striped magnetic domain, 5 is the stable position of the VBL pair, 1 is the VBL pair, 21 is the jittery conductor button for bit fixing, and 25 is the bit fixing current. The striped magnetic domain 12 is stabilized around the groove 11, and the domain wall 13 outside of the striped magnetic domain 12 becomes a transfer path for the VBL pair.

When a current 25 is passed through the zigzag conductor pattern 21, a local in-plane magnetic field is generated, and a stable position 5 of the VBL pair is formed under every other conductor.

The transfer of the VBL pairs is performed by applying a pulsed bias magnetic field to the striped magnetic domains to move the domain walls in the normal direction of the striped magnetic domains, and by utilizing the accompanying gyroscopic force that causes the VBL pairs to slide laterally within the domain walls. However, in the case of a rectangular-wave bias magnetic field pulse, when the stripe magnetic domain returns to its original state at the fall of the pulse, the VBL pair moves in opposite directions, and the total amount of movement becomes almost zero. Therefore, as shown in FIG. 4, the fall time of the bias magnetic field pulse 31 is lengthened,
The return of the VBL pair is suppressed to ensure unidirectional movement of the VBL pair.

(Problem to be Solved by the Invention) However, the moving distance of the VBL pair is proportional to the amount of movement of the striped domain wall, and it not only depends on the operating conditions such as the magnitude of the pulsed bias magnetic field and the rise time, but also the moving distance of the striped domain wall. It also depends on the pinning method and the static bias magnetic field applied to hold the striped domains. Therefore, if the direction of the pulsed bias magnetic field is not appropriately selected, the transfer margin of the VBL pair may decrease if the moving distance of the VBL pair is short.

An object of the present invention is to provide a method for driving a magnetic memory element that solves this problem.

(Means for Solving the Problems) The gist of the present invention is to form a ferromagnetic (including ferrimagnetic) film whose easy magnetization direction is perpendicular to the film surface.
The striped magnetic domains are held by a static bias magnetic field perpendicular to the film surface, and a pulsed bias magnetic field is applied in the direction perpendicular to the film surface, thereby creating two adjacent two domains in the Bloch domain walls at the boundaries of the striped magnetic domains. VB consisting of two vertical Bloch lines
In a method for driving a magnetic memory element that transfers and holds L pairs as storage carriers, the pulsed bias magnetic field is applied in the same direction as the static bias magnetic field.

(Function) The transfer margin of the VBL pair decreases because the domain wall of the stripe domain contracts or expands in the normal direction due to the demagnetizing field from the stripe domain itself or the stripe domain fixing means. This is due to the fact that the effective magnetic fields that act are different, and a sufficient amount of movement of the domain wall cannot be secured for the same pulsed bias drive magnetic field. By applying a pulsed bias magnetic field in the same direction as the static bias magnetic field, the domain wall can be moved largely in its normal direction, giving the VBL pair a sufficient moving distance.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are pulse waveform diagrams showing one embodiment of the present invention. To explain the present invention using FIGS. 1 and 3, striped magnetic domains are formed around the groove 11 dug into the garnet film, stabilized by a static bias magnetic field with the polarity of 32 in FIG. 1(b). The outer domain wall 13 of 12 is VB
A current is passed through the zigzag conductor 21 to generate a local in-plane magnetic field to form a stable position 5 of the VBL pair on the domain wall 13, and a static bias magnetic field 32 is applied from the outside. The pulsed bias magnetic field of FIG. 131 in the same direction is applied to transfer VBL pair 1 to the next stable position 5.

FIG. 2 is a diagram showing the effect of the above embodiment, and shows the pulsed bias drive magnetic field margin characteristics of BL vs. transfer in a straight domain wall soil of a device using a 5 pm bubble material. In the figure, the vertical axis represents a static bias magnetic field, and the horizontal axis represents a pulsed bias drive magnetic field.

A current of 3 mA was passed through the zigzag conductor batts having a width of 1.2 pm and a gap of 1.2 μm to form a stable position of a VBL pair with a period of 4.8 pm. In the direction perpendicular to the film surface, the rise time is 50 ns, the pulse flat part is 300 ns, and the fall time is 800 ns.
A pulsed bias driving magnetic field of ns was applied in the same direction as the static bias magnetic field, that is, in the direction in which the striped magnetic domains contracted, to obtain the margin shown in FIG. The margin shown by the broken line in FIG. 2 is the margin when the pulsed bias drive magnetic field is applied in the opposite direction to the static bias magnetic field.

By applying the pulsed bias drive magnetic field in the same direction as the static bias magnetic field, the transfer margin of the VBL pair was greatly improved.

(Effects of the Invention) As described above, the present invention defines the polarity of the pulsed bias driving magnetic field for driving the VBL pair, and largely moves the domain wall of the striped magnetic domain in the normal direction thereof.
A large operating margin can be obtained by giving the BL pair a sufficient travel distance.

In addition, in this example, VB due to the current flowing through the zigzag conductor
Although the L-pair stabilization method was used, it is clear that similar effects can be obtained even when a battened in-plane magnetization film or the like is used.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are pulse waveform diagrams showing one embodiment of the present invention, Figure 2 is a diagram showing measurement results of pulsed bias magnetic field margin characteristics of VBL versus transfer, and Figure 3 is a diagram showing striped magnetic domains. and a batan diagram showing an example of a method for stabilizing the VBL pair,
FIG. 4 is a pulse waveform diagram showing a conventional method of driving a magnetic memory element. In the figure, 1... vertical Bloch line pair, 5...
Stable position of vertical Bloch line pair, 11... Groove dug into garnet, 12... Striped magnetic domain, 13.
...Domain wall, 21...Zigzag conductor slam, 25...
Current for bit fixing, 31...bias magnetic field pulse,
32... Static bias magnetic field.

Claims (1)

[Claims] In a ferromagnetic (including ferrimagnetic) film whose easy magnetization direction is perpendicular to the film surface, the striped magnetic domain is maintained in a static bias magnetic field perpendicular to the film surface, and In a method for driving a magnetic memory element in which a pulsed bias magnetic field is applied to transfer and hold a vertical Bloch line pair consisting of two adjacent vertical Bloch lines formed in a Bloch domain wall at the boundary of the striped magnetic domain as a memory carrier. . A method for driving a magnetic memory element, characterized in that the pulsed bias magnetic field is applied in the same direction as the static bias magnetic field.