The switchable memory element
(57) Abstract:The invention relates to the field elements of automation and computing, in particular for magnetic thin-film memory and switching elements. The aim of the invention is to expand the functional capabilities of the storage element. This goal is achieved by the fact that located above the strip center conductor 9 applied in relation to it so that the magnetic field from leaking in it current coincides in direction with the axis of easy magnetization of a thin-film magnetoresistive layers 5, 6, and thin-film magnetoresistive layers 5, 6 have different values of the field magnetic anisotropy and the ratio of the larger field magnetic anisotropy smaller is at least four. 2 C.p. f-crystals, 4 Il. The present invention relates to the field elements of automation and computing, in particular for magnetic thin-film memory and switching elements.Known magnetoresistive memory (see U.S. patent N 4751677, G 11 C 11/15) using anisotropic magnetoresistive (AMR) effect, on the basis of the two-layer magnetic films FeNiCo with semiconductor shchina effect, equal (2-3)% and, as a consequence, a sufficiently high demands on technology to obtain acceptable signal reading.Known (see J. M. Daugthon. Magnetoresistive memory technology. Thin solid films, 216, 1992, p. 2705-2710) 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. When SVMR 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, and not on the angle between the vectors magnetized magnetic film and flowing through her current, as in the AMR effect. The second feature SVMR effect is that the maximum difference of the resistances of the magnetic films corresponds to the parallel and antiparallel to the location of the vectors of magnetization of adjacent magnetic films, in contrast to the perpendicular position between the vectors of magnetization and current for the AMR effect. The minimum resistance corresponds to the parallel arrangement of the vectors of magnetization magnetic is th effect. Value SVMR effect on samples with films of Fe15Ni65Co20about 42% for 10 magnetic layer at room temperature (J. M. Daugthon and Y. J. Chen. GMR materials for low field applications. IEEE Trans. Magn. v.29, N6, p. 2705-2710). However, to use SVMR effect it is necessary to paramagnetically only one magnetic film of the two. To do this, increase the coercive force of one of the magnetic films due to the exchange interaction with additional magnetic film, for example, 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 force. The rapid increase obtained SVMR effect occurring at the present time, due to the large amount of ongoing developments in the world in this area of research, leading to the possibility of using structures based on the memory element with SVMR effect as switching elements due to the presence of such patterns of threshold characteristics.The aim of the invention is to expand the functional capabilities of the storage element by giving it the properties of a switching element.Phnom effect, containing a silicon substrate on which are successively located the first insulating layer at least one strip with pointed ends, containing two protective layers separated by at least one structure comprising two spaced one above the other thin-film magnetoresistive layers with the axis of easy magnetization and located between the thin-film layer of copper, the second protective and insulating layers, conductive layer with a Central conductor passing over the strip, and the third protective layer, the specified center conductor is perpendicular to the axis of easy magnetization of thin-film layers of strips, and thin-film magnetoresistive layers of the strips have different values of the field magnetic anisotropy. In this respect a large field magnetic anisotropy smaller coincides at least four strip may contain multiple structures, each of which includes two thin-film magnetoresistive layer and located between the thin-film copper layer, and the element itself may consist of several parallel connected stripes.Salient features of the above together, leading to magnicifent thin-film magneto-resistive layer strips and execution of 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 the storage element threshold characteristics, it can be used as a switching element with memory at low drive currents. Threshold characteristics, as shown by the following calculations appear in structures in which the direction of the magnetic field from flowing in the current conductor coincides with the direction of the axis of easy magnetization (old) magnetic films, while in the storage elements is perpendicular to the direction of the magnetic field of the conductor and on. 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 the exchange interaction, the introduction of the same into a strip of several structures of the magnetoresistive layers, separated by layers of copper, dramatically increases the spin-valve effect. The use of multiple parallel-connected strips can increase the current element (the current through the strips) to a value sufficient to control the next element. This allows with the tion is illustrated by drawings, where in Fig. 1 shows the structure of a switching element on SVMR effect in the context of Fig. 2 topology strips with two structures of the two magnetoresistive layers separated by a layer of copper; Fig. 3 topology element with two parallel strips of Fig. 4 design characteristics of the switching element of Ie(ICR)/UPete=onst, where Iethe current through the strip, ICRthe current through the conductor, UPetethe voltage applied to the strip (item) for (a) UPete27 mV and (b) UPete108 mV when the resistance strips 270 Ohms, the ratio of the length of the strip to a width of 3 for the case when an directed along the strip.A switching element with a memory for SVMR effect contains (Fig. 1) the silicon substrate 1, on which are positioned successively the first insulating layer 2, a strip with pointed ends, consisting of two protective layers 3, 4, two magnetoresistive magnetic layers 5, 6 and a copper layer 7. On top of the strips are positioned successively insulating layer 8, the conductive layer 9 with the Central conductor and the second protective layer 10. In Fig. 2 shows the topology of a strip containing two structures with magnetoresistive layers. The strip consists of two protective aqueous layer of copper I1, separating structure. The topology element with two stripes (Fig. 3) includes two parallel connected conductors 12, 13 strips 14, 15 and passes over the strips 14, 15 of the Central conductor 16.The work of the switching element depends on the direction on magnetic films relative to the strips. There are two cases: an directed along or across the strips. Let us first consider the method used for estimating the characteristics of a switching element with memory, based on theory of micromagnetism.Calculation of the parameters of the element is carried out in two stages determine the distribution of the magnetization in both the Mr films depending on magnetic fields generated by currents control, and process variation from the condition of minimum energy (E) system of two magnetic films and, further, calculation of the signals read (USCfor data touch currents read (ISaint) and the external magnetic field (HNR).We used a model in which the distribution of the magnetization is read constant along the Mr film, which is a rather rough approximation. One of the important consequences of this approximation will overestimate the calculated values of the fields once the Noi film (Minand discounttravel magnetic film (Mn) from the edges of the strips, which reduces the values of these fields.The energy of the system of two Mr films equal
E Ek+ Em+ Er+ Eh< / BR>< / BR>where
Ekenergy azonitrile, Emmagnetostatic energy, Erthe interaction energy of two Mr films, Ehthe energy in the external magnetic fields, including fields from the touch current, H HNR+ HSaintKin,nthe magnetic anisotropy constants of the upper and lower magnetic films,in,nthe thickness of the Mr film,in,nthe angles between ALN and Minand MnHpinnfield demagnetization occurring at the edges of the stripes:
< / BR>whereininthe surface density of magnetic charges on the edges of the film.Search for Emin(in,nis brute force under given initial conditions Minand Mn.An directed along the strips. Work switchable element is as follows. We believe that in the initial state in the absence of current through the strip of the magnetization in the two magnetic films 5,6 are antiparallel to each other. Recorded in the item information is otnositelno strips. The recording media is feeding into the Central conductor current of a certain polarity. To reduce the magnitude of the write current possible supply of striped additional current of a certain polarity. Work element as a switching is illustrated by the calculated characteristics (Fig. 4), obtained, for greater clarity, when the value SVMR effect 200% for the case when an magnetic film is located along the strip, and the Central conductor across. Value SVMR effect only affects the differential currents between the closed and open States. The control node in the element is a conductor, the control is flowing in it current. The characteristic element in the switching mode is hysteretic, with distinct thresholds switch. The switching element is carried out by the magnetization reversal discounttravel magnetoresistive film under the action of the magnetic field created by the current in the Central conductor 9. After the termination of the current in the Central conductor discountcanada film is not over magnetize in the opposite condition, which determines the hysteresis characteristics. When the supply current reverse polarity discountcanada film pen is magnetic films 5, 6 does not lead to the destruction of recorded information, because "O" or "I" is determined by the direction of the magnetization vector vysokorentabelnoy film, which is not over magnetize when the switching element. The state with antiparallel directed vectors of magnetization of the magnetic films corresponds to the maximum resistance of the strips, i.e., when this element is in the "closed" state, and the state with parallel arrangement - minimum resistance strips, i.e., when this element is in the "open" position. The hysteresis element with an along the strip means storing information due to the stability of both States discounttravel film in the absence of currents control without destroying the information defined by the direction of the magnetization vector vysokorentabelnoy film. This creates new functionality to the application of the proposed element, for example, as logic elements. The presence of the strip several structures of low and vysokooleofobnyh magnetoresistive layers separated by a layer of copper, does not change the physics of the item, and also leads to an increase SVMR effect. In the structure with several parallel connection is leave a manifold increase in the current element, it can be used to control the next element.It is evident from Fig. 4 shows that for this version of the element with increasing UPetethere is a reduction of the switching threshold. This is because the increase of the current flowing through the magnetoresistive layers currents leads to an increase in the deflection angle of the magnetization vector discounttravel film from an that facilitates switching of magnetization. However, increasing the deviation of the magnetization vector from an leads to a decrease in the differential resistance between the closed and open States, i.e. there is an upper limit UPetefor the element.An directed crosswise strips. This option has a number of differences from the above:
1. Threshold characteristics flatter, i.e., a complete switching occurs when several large drive currents. This is due to significantly large demagnetizing fields, which leads to profitability gradual deviation of the magnetization vector discounttravel magnetic film.2. There is a reverse effect depends on the switching current from the supply voltage, since the magnetic fields generated by flowing in the magnetic films currents will be prepjatstvovanie with two parallel along an vectors of magnetization in this case is unstable due to large values of demagnetizing fields.To create a high magnetic anisotropy can be used alloy Fe15Ni65Co20used in magnetoresistive memory elements and which 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 the same 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 claimed switching element with a memory for SVMR effect has a threshold characteristics and memorization, which allows to extend the field of application for use in logic circuits, etc., One of the promising applications of such elements use in single-chip magnetoresistive storage devices with random sampling of controls. 1. Switchable element with memory on the spin-valve magnetoresistive effect containing a silicon substrate on which are successively arranged first insulating layer, a strip containing two protective layers separated by at least one structure consisting of two who between them thin-film layer of copper, the second insulating layer, a conductor layer with a Central conductor passing over the strip, and the third protective layer, characterized in that the Central conductor is perpendicular to the axis of easy magnetization of the magnetoresistive film strips, magnetoresistive film have different values of the field magnetic anisotropy, and a larger field magnetic anisotropy smaller is at least four.2. Item under item 1, characterized in that the strip contains several structures, consisting of two magnetoresistive films and located between the thin-film layer of copper, separated by a thin-film layers of copper.3. Item under item 1, characterized in that it contains several parallel strips.
FIELD: magnetic microelements and nanostructures, possible use in sensors of magnetic field and current, recording and logical elements, galvanic cross couplings and spin transistors based on multi-layered thin-film nanostructures with anisotropic or gigantic magneto-resistive effect.
SUBSTANCE: multi-layer thin-film magneto-resistive nanostructure contains first protective layer, upon which first magneto-soft film is positioned, separating non-magnetic layer on top of first magneto-soft film, on top of which in turn second magneto-soft film and second protective layer are positioned, between second magneto-soft film and second protective layer a layer of silicon carbide is positioned, while separating non-magnetic layer is thick enough to prevent interaction of exchange between magneto-soft films.
EFFECT: creation of multi-layer thin-film magneto-resistive nanostructure, having various reverse magnetization fields of magnetic layers included in it, having high reproducibility of magnetic parameters and expanded functional capabilities.
FIELD: magnetic micro- and nano-elements, possible use in indicators of magnetic field and current, memorizing and galvanic elements, galvanic decoupling and spin transistors based on multi-layered nanostructures with magneto-resistive effect.
SUBSTANCE: in multi-layered magneto-resistive nanostructure composed of magnetic nano-islands, consisting of N pairs of alternating layers, each pair containing layers of nano-islands with different values of magnetic reversal field of magnetic materials positioned on dielectric layer and protected by a solid dielectric layer on top. Such a multi-layered magneto-resistive nanostructure consists of nano-islands positioned separately within each layer. Nano-islands of each layer may contact nano-islands of upper and lower layers, with resulting magnetic interaction between them.
EFFECT: production of multi-layered magneto-resistive nanostructure using magnetic nano-islands, having high value of magneto-resistive effect in small magnetic fields and having high reproducibility of magnetic parameters for serial production of nano-elements based on aforementioned structure.
2 cl, 6 dwg
FIELD: physics, computer engineering.
SUBSTANCE: invention can be applied as external and internal data carrier furnished with reading device. Offered device contains cylindrical body consisting of bottom and top cover, and the platform superadjacent with the body, cylindric cartridge, contact reading unit in the form of read and record head assembly system embedded from above and from below in rectangular frames interconnected with thin pins. The device is supplied with rotary engine simultaneous rotating platform and data carrier cartridge fixed thereupon. Lower rigid segment of the engine is fixed on body bottom, while its mobile part is mounted on body axis and rigidly connected to the platform. The head assembly contains the case clamped to constant magnets with sliding enclosure, and the head case is supplied with flexible belts with their end containing pads with the heads in-between with contacts providing signal transmission from heads through the converter to mobile contacts of heads. Each head is connected with two strings supplied with reading signal transmission paths. Heads are integrated in units with magnet-insulating walls and spaced between upper and lower frames in parallel to spokes supplied with electromagnetic windings interacting with constant magnets of the heads. The cover of the device body accommodates barometric filter with the filter thereunder.
EFFECT: higher capacity and reliability of the device.
4 cl, 9 dwg
SUBSTANCE: multilayer magnetoresistive composite nanostructure has several sets of alternating layers of magnetically soft and magnetically hard nanoclusters insulated at the top and bottom by a continuous dielectric layer of antiferromagnetic material. One set has an antiferromagnetic layer, a layer of magnetically soft nanoclusters, an antiferromagnetic layer, a layer of magnetically hard nanoclusters, and a antiferromagnetic layer, where thickness of the nanocluster film is equal to 0.8-2.5 nm. The number of said sets of layers is between 2 and 5.
EFFECT: design of a magnetoresistive nanostructure whose production technology guarantees required parametres, giant magnetoresistive effect in the material with working capacity under high temperature conditions, and high reproducibility of parametres under batch production conditions.
5 cl, 2 dwg
FIELD: physics, computer engineering.
SUBSTANCE: invention relates to computer engineering. A method of writing in a memory device comprising a plurality of magnetoresistive random access memory (MRAM), wherein each MRAM cell to be written by using a thermally-assisted switching (TAS) write operation, includes a magnetic tunnel junction (MTJ) having a resistance that can be varied during a write operation when the MTJ is heated to a high threshold temperature, and a selected transistor electrically connected to the MTJ; a plurality of word lines and bit lines connecting MRAM cells along a row and a column, respectively; the method comprising supplying a bit line voltage to one of the bit lines and a word line voltage to one of the word lines for passing a heating current through the MTJ of a selected MRAM cell; once the MTJ has reached the high threshold temperature, varying the resistance of the MTJ; and cooling the MTJ to freeze said resistance in its written value; said word line voltage is a word line overload voltage which is higher than the base operating voltage of the MRAM cells such that the heating current has a magnitude that is high enough for heating the MTJ to the predetermined high threshold temperature.
EFFECT: reduced power consumption when writing in a memory device.
8 cl, 3 dwg
FIELD: physics, computer engineering.
SUBSTANCE: invention relates to computer engineering. A magnetic element to be written using a thermally-assisted switching write operation comprises a magnetic tunnel junction formed from a tunnel barrier being disposed between first and second magnetic layers, said second magnetic layer having a second magnetisation the direction of which can be adjusted during a write operation when the magnetic tunnel junction is heated to a high threshold temperature; an upper current line connected at the upper end of the magnetic tunnel junction; and a strap portion extending laterally and connected to the bottom end of the magnetic tunnel junction; the magnetic element further comprising a bottom thermal insulating layer extending parallel to the strap portion and arranged such that the strap portion is between the magnetic tunnel junction and the bottom thermal insulating layer.
EFFECT: reduced heat loss in the magnetic tunnel junction.
14 cl, 7 dwg
FIELD: physics, computer engineering.
SUBSTANCE: present invention provides a magnetic memory element (1) which is suitable for a writing operation with thermal switching, comprising a current line (4) in electrical communication with one end of a magnetic tunnel junction (2), where the magnetic tunnel junction (2) comprises: a first ferromagnetic layer (21), having a fixed magnetisation; a second ferromagnetic layer (23) having magnetisation which can be freely set up with a given high temperature threshold; and a tunnelling barrier (22) which is provided between the first and second ferromagnetic layers (21, 23); where the current line (4) is adapted to transmit heating current (31) through the magnetic tunnel junction (2) during a write operation; where said magnetic tunnel junction (2) further comprises at least one heating element (25, 26) adapted to generate heat when heating current (31) passes through the magnetic tunnel junction (2); and a thermal barrier (30) in series with said at least one heating element (25, 26), where said thermal barrier (30) is adapted to limit heat generated by said at least one heating element (25, 26) within the magnetic tunnel junction (2).
EFFECT: producing a magnetic memory element (1) suitable for a write operation with thermal switching.
11 cl, 2 dwg
SUBSTANCE: magnetoresistive memory cell comprises a remagnetisable layer and a non-remagnetisable layer separated by a barrier layer, and writing and reading means. The memory cell further includes a fastening layer made of p- or n-type semiconductor material, the next layer of semiconductor material with an opposite type of conductivity, forming a p-n junction, comprises an address line and a bit line, situated on both sides of the listed layers of the memory cell, means of generating write currents in the address and bit lines, reading means in the form of means of measuring electrical resistance of the memory cell, as well as means of setting polarity and the value of relative electrical bias between the address and bit lines.
EFFECT: simple technique of making a magnetoresistive memory cell.
2 cl, 1 dwg
FIELD: physics, computer engineering.
SUBSTANCE: invention relates to electronics, particularly to a method of recording and reading more than two bits of data for a magnetic random access memory (MRAM) cell. A MRAM cell comprises a magnetic tunnel junction formed from a read magnetic layer having a read magnetisation, and a storage layer comprising a first storage ferromagnetic layer having a first storage magnetisation, a second storage ferromagnetic layer having a second storage magnetisation. The method includes heating the magnetic tunnel junction over a high temperature threshold; orienting the first storage magnetisation at an angle relative to the second storage magnetisation for the magnetic tunnel junction to reach a resistance state level determined by the orientation of the first storage magnetisation relative to the orientation of the read magnetisation; and cooling the magnetic tunnel junction.
EFFECT: enabling storage of at least four distinct state levels in a MRAM cell using only one current line to generate a writing field.
15 cl, 14 dwg
FIELD: computer engineering.
SUBSTANCE: invention relates to computer engineering. Magnetic random access memory (MRAM) cell comprises a tunnel magnetic junction having the first ferromagnetic layer, the second ferromagnetic layer with the second magnetization, which can be oriented relative to the axis of anisotropy of the second ferromagnetic layer at a predetermined high-temperature threshold, and a tunnel barrier between the first and the second ferromagnetic layers; the first current transmission line extending along the first direction and being in communication with the tunnel magnetic junction; herewith the first current transmission line is configured able to provide the magnetic field to orient the second magnetization while transferring the field current; wherein the MRAM cell is configured relative to the first current transmission line in such a way, that while providing the magnetic field at least one magnetic field component is perpendicular to the said axis of anisotropy; the second ferromagnetic layer is of asymmetric shape along at least one of its dimensions, so that the second magnetization contains the pattern of C-shape condition.
EFFECT: technical result is the reduction of power consumption and improved dispersion of the switching field.
12 cl, 6 dwg