A storage element on the spin-valve magnetoresistive effect

 

(57) Abstract:

The invention relates to the field of computer technology, in particular to magnetic storage devices with random access. The essence: a storage element containing two discretetime conductors, such as copper, are located respectively between the three-layer strip and the first protective layer and three-layer strip and the second insulating layer and separated on the plot, free from the three-layer strip, the third insulating layer, and a thin-film magnetoresistive layers have different values of the field magnetic anisotropy and the ratio of the larger field magnetic anisotropy smaller is at least four. 3 Il.

The present invention relates to the field of computer technology, in particular to a magnetic thin film storage devices with random access.

Known magnetoresistive memory (see U.S. Patent N 4751677, M CL5G 11 C 11/150) using anisotropic magnetoresistive (AMR) effect, on the basis of the two-layer magnetic films FeNiCo with solid state control circuits on the same substrate. The disadvantages of memory cells is high requirements for technology to obtain acceptable signal reading.

Known (see A. V. Pohm, C. S. Comstock. Memory implications of the spin-value effect in soft Board. J. Appl. Phys. 69(8), 1991, p.p. 5760-5762) a storage element on the spin-valve magnetoresistive (SVMR) effect, we adopted as the prototype of the proposed technical solutions, designed as a multi-layer strip with the main part of the two magnetoresistive films of Fe15Ni65Co20separated by a layer of copper, which is in the reading mode is included in the circuit of the bridge. When SWMR-the effect of the change in resistance depends on the angle between the vectors of magnetization of adjacent magnetic films separated by a layer of copper. Value SVMR effect on samples with films of Fe15Ni65Co20reaches (5,5-7,5)% when the thickness of the magnetic film of about 8 nm and the thickness of the copper layer of 5 nm. However, to use SWMR-effect, it is necessary to paramagnetically only one magnetic tape. To do this, increase the coercive force of one of the films due to the exchange interaction with additional magnetic film, such as FeMn film. In the above-mentioned storage element uses two film FeNiCo, and in his description not specified the way to obtain films with different values of magnetic anisotropy or coercive what about the influence of the copper film, because the current in the strip runs parallel to the two magnetoresistive or copper film, and the resistance of the copper film always small compared with the resistance of the magnetic films.

The technical result is the increased functionality of the storage element and the simplification of its manufacturing technology.

The technical result is achieved in that the storage element on the spin-valve magnetoresistive effect containing a silicon substrate on which are successively arranged first insulating layer, the first protective layer, three-layer strip with pointed ends, consisting of two spaced parallel to the substrate a thin-film magnetoresistive layers with the axis of easy magnetization directed along the strip and located between the thin-film layer of copper and a layer of three-layer strip is second insulating layer, which is formed conductor and the second protective layers is further provided with two discretetime conductors, such as copper, located respectively between the three-layer strip and the first protective layer and three-layer strip and the second insulating layer and divided between esistive layers sandwich the strips have different values of the field magnetic anisotropy. The ratio of the larger field magnetic anisotropy smaller is at least four.

Salient features of the above together is the presence of two discrediting conductors located on both sides of the three-layer strip and separated by an additional insulating layer, and performing a thin-film magnetoresistive layers with different values of the field magnetic anisotropy.

The essence of the invention lies in the fact that the proposed structure provides a current flow perpendicular to surfaces of layers of the element, and not along them, as in the known device, and thus, thin-film copper layer between the magnetoresistive layer in three-layer strip is connected in series to them, not in parallel, eliminating the shunting effect of copper layer and increases the observed Suprefact that, in turn, leads to a sharp increase in signal reading. The use of magnetoresistive layers with different values of the field magnetic anisotropy eliminates the need for additional FeMn film to increase the coercive force of one of the magnetic films due to exchange vzaimodei SVMR effect in section, in Fig. 2 storage elements included in the circuit of the bridge, top view, and Fig. 3, the circuit element in the trigger.

A storage element for SVMR effect contains (Fig. 1) the silicon substrate 1, on which are positioned successively the first insulating layer 2, the first protective layer 3, the first discreditably conductor 4, the third insulating dielectric layer 5, a three-layer strip with pointed ends, consisting of two layers of magnetoresistive magnetic films 6, 7 and a copper layer 8. On top of the three-layer strip is the second discreditably Explorer 9. Above are consistently the second insulating layer 10, the conductive layer 11 and the second protective layer 12.

When reading in a bridge circuit uses four magnetoresistive storage element 13-16 (Fig. 2), and the use of trigger schemes strips 17, 18 with conductors 19, 20 is connected to the trigger of the transistors 21, 22 with the keys 23-26 (Fig. 3).

Working storage element is as follows. In the absence of current through the three-layer strip (touch current) and the current through the conductor 11, the magnetization in the two magnetic films is or antiparallel to each other when recorded in sapam, 9 leads to the fact that the touch current to flow perpendicularly through the three-layer strip, and not along it, as was in the previous structures, in which the pads were on the pointed ends of the strips. Thus, current passes successively through two magnetoresistive and the copper film, and not in parallel.

We introduce the notion of the value of physical SVMR effect, characterized by magnitude , and the magnitude of the observed SVMR effect, characterized by the value of (/)neb. Under physical SVMR effect will be to understand the magnitude of the effect inherent in the magnetoresistive strip with resistance Rm:

(/)Phys= Rm/Rm(1)

where Rmthe maximum change in resistance strips.

Under the observed SVMR effect will be to understand the magnitude of the measured effect in a concrete structure with a resistance R and a maximum resistance change R:

(/)neb=(R(Rm+Rm)-R(Rm))/R(Rm)= R/R

In the case of already known storage element, as mentioned above, two magnetic and copper foils (RCu) connected in parallel and the resistance of this structure is:

R1)(Rm)=RmRCu/ (Rm+2R
< / BR>
Denoting by p=RCu/Rmand taking into account (1) we get:

(/)Phys= (1+2p)(/)(1)neb/[2p-(/)(1)neb(4)

For (/)(1)neb= (5,5-7,5) % and p (0,2-0,25)

(/)Phys= (23-33) %

In the proposed storage element two magnetic and copper foils are connected in series and the total resistance R(2element is:

R2)(Rm)=2Rm+RCu< / BR>
The resistance change is:

< / BR>
Here

< / BR>
Finally:

(/)(2)neb= 2(/)Phys/(2+RCu/Rm) (4)

Thus, the ratio between the observed values SVMR effect in the proposed and known storage elements taking into account expressions (2)-(4) the following:

< / BR>
This leads to the fact that for the ratio Rm/RCu=4-5 observed SVMR effect increases with (5,5-7,5)% to (20-30)% However, this direction of flow of the touch current disappears its impact on the alternating magnetization of the magnetic films. Remains in effect only for the current through the conductor 11, which creates a magnetic field along the axis of easy magnetization (OLN). Therefore, in the recording mode is pulse necessary to write "0" or "1" polarity only in the conductor 11. Because of the differences before overwrite "0" to "1". With increasing drive current will occur alternating magnetization film with a large value of the field magnetic anisotropy, which would mean reverse alternating magnetization "1" to "0", and this is unacceptable. Thus, when overwriting "0" to "1" there is some range of acceptable currents account. When rewriting "1" to "0" is current of reverse polarity, which paramagnetism film with the least amount of field magnetic anisotropy, the film is more value field magnetic anisotropy field cannot paramagnetic. Restrictions on the magnitude of the currents account still.

Reading of information is possible in various ways, for example using the bridge and trigger circuits. When reading information in a bridge circuit required power reading. The storage elements 13-16 (Fig. 2) included in the bridge circuit, and the elements 13, 15 recorded "1", and the elements 14, 16 is "0" that can be taken for writing information "1" in the bridge. Then the information "0" correspond to the opposite condition of items 13-16. The information read from the bridge, the sign of the signal read. In the bridge circuit and the conductors 11 is fed a current pulse, and in the conductors 11 elements 13, 16 and 14, 15 pulses currents have opposite polarity. In Chodit deviation of the magnetization vectors from ALN, that will lead to a decrease in resistance of one pair of strips and increase the resistance of the other pair of elements. As a result, when reading "0" is read positive signal read, and when reading a "1" is a negative signal.

There is another version of the construction of the memory cell (Fig. 3) replacing the lower arms of the bridge (14 and 15 in Fig. 2) the transistors 21, 22, components with a three-layer strips 17 and 18 in the presence of cross-symmetric positive feedbacks trigger. The account information is as in prejudism case, magnetization reversal discountcanada magnetoresistive layer under the action of the current pulse of the desired polarity to the conductors 19 and 20, and the strip is written the opposite information. Reading is as follows. When the supply voltage to the trigger through the keys 24 and 26, the trigger is set to one of two possible States defined by the difference in the values of the resistors, which are three-layered strips 17 and 18. Voltage from the collectors of transistors 21 and 22 through the open at this time, the keys 23 and 25 act to read information. The advantage of this option in the large signal value read, simplifying pasisonate alloy Fe15Ni65Co20used in magnetoresistive elements and allows to obtain the value of the field magnetic anisotropy up to 20 e, and with increasing cobalt content up to 30% of the field magnetic anisotropy reaches 40 e, to create a layer with a small amount of field magnetic anisotropy can be used permalloy Fe20Ni80giving the magnitude of the field magnetic anisotropy from 2 to 5 E.

Thus, the advantage of the inventive storage element on SVMR effect is the increase of signal readout, which allows to apply the new scheme of memory cells and the simplification of the structure, because there is no need for additional magnetic film, which increases the density of information, reducing the technological difficulties of element production and lowering power consumption.

1. A storage element on the spin-valve magnetoresistive effect containing a silicon substrate on which are successively arranged first insulating layer, the first protective layer, three-layer strip with pointed ends, consisting of two spaced parallel to the substrate a thin-film magnetoresistive layers with the axis of easy magnetization directed by wdstory insulating layer, which formed conductor and the second protective layers, characterized in that it has two discretetime conductors, such as copper, are located respectively between the three-layer strip and the first protective layer and three-layer strip and the second insulating layer and separated on the plot, free from the three-layer strip, the third insulating layer, and a thin-film magnetoresistive layers have different values of the field strength of the magnetic anisotropy.

2. Item under item 1, characterized in that the ratio of the greater magnitude of the field strength of the magnetic anisotropy to the lesser of at least 4.

 

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