JPH0642317B2 - Superconducting memory - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a superconducting memory device for storing information in the superconductor in the form of Abrikosov magnetic flux quanta.

[Conventional technology]

A device that uses Abrikosov flux quanta as memory information is
Japanese Patent Publication No. 60-34194 and Applied Physics Letters, Vol.39 NO.12 Desember 1
981, pp. 992-993).

FIG. 7 is a schematic perspective view showing one of the conventional examples of the Abrikosov magnetic flux quantum memory device. A thin superconductor film 51 for holding Abrikosov magnetic flux quanta, and a Josephson junction 53 for magnetic flux quantum detection, in which a part of the superconductor film 51 is a lower electrode and the superconductor film 52 is an upper electrode. , The magnetic flux quantum write line 54 provided near the end 55 of the superconductor layer 51.
And a superconductor film 51 'that is thicker than the superconductor film 51 surrounding the periphery except the end 55 of the superconductor film 51. Note that B conceptually represents the Abrikosov magnetic flux quantum retained in the superconductor film 51.

This Abrikosov magnetic flux quantum memory device has a superconductor film 51.
The presence / absence of the Abrikosov magnetic flux quanta held therein is associated with "1" and "0" in the memory state. That is, when the Abrikosov magnetic flux quantum is retained in the superconductor film 51,
The fact that the magnetic flux quantum influences the Josephson junction 53 to reduce the threshold current in the Josephson junction 53 is used, and the change in the threshold current is changed to "1" in the memory state.
It corresponds to "0".

Information is read by applying a bias current having an appropriate value to the Josephson junction 53. That is, when a bias current having a value between the threshold current when the Abrikosov magnetic flux quantum is held in the superconductor film 51 and the threshold current when the Abrikosov magnetic flux quantum is not held is given to the Josephson junction 53,
If the Abrikosov magnetic flux quantum is held, a voltage is generated in the Josephson junction 53 (voltage state), and if not held, the voltage becomes zero (zero voltage state).

[Problems to be solved by the invention]

However, this conventional Abrikosov magnetic flux quantum storage device has a very serious problem in writing.

To write the memory state “1”, a current is applied to the write line 54 in a predetermined direction to generate a magnetic field, and the superconductor film 51 has an end 5 at the end 5.
This is achieved by internally generating Abrikosov flux quanta from 5 in a predetermined direction (for example, upward). on the other hand,
Writing of the storage state “0” must be performed using a different procedure depending on the storage state at that time. That is, if the storage state before writing is “1”, a reverse current is applied to the write line 54 to cause downward flux quanta to be generated in the superconductor film 5.
Abrikosov magnetic flux quantum number is made zero by internally generating 1 and annihilating the upward magnetic flux quantum. Also,
If the memory state is "0", no current is passed through the write line 54 to maintain the state as it is, and "0" is written.

As described above, in the conventional Abrikosov magnetic flux quantum storage device, it is necessary to read the storage state each time before writing, and if the access time for writing is unnecessarily lengthened and a computer is configured using this storage cell, the machine cycle time There was a problem that it becomes longer.

In addition, when writing "0" from the memory state "1", it is very difficult to exactly eliminate the pair of magnetic flux quanta. If the pair annihilation is insufficient, a part of the upward Abrikosov magnetic flux quantum remains, and if the pair annihilation is excessively performed, the downward Abrikosov magnetic flux quantum is retained. Therefore, the write operation margin is extremely narrowed due to the necessity of annihilating the Abrikosov magnetic flux quanta without excess or deficiency, and stable operation is difficult. In addition, there is a problem in that residual Abrikosov magnetic flux quanta, which have not been completely pair-annihilated, gradually accumulate during repeated write operations, resulting in malfunction.

[Means for solving problems]

The superconducting memory device of the present invention has been made in view of the above-mentioned problems, and it is possible to generate an Abrikosov magnetic flux quantum internally by applying a magnetic field, and to hold the Abrikosov magnetic flux quantum by itself even when the magnetic field is removed. An information storage means having a conductor layer, and an information writing means having a superconductor layer for generating a magnetic field applied to the superconductor layer of the information storage means when a current corresponding to information is applied, At least one Josephson junction element sensitive to the magnetic field created by the Abrikosov flux quantum self-held in the superconducting layer of the information storage means, and the tunnel barrier layer of the Josephson junction element of the magnetic field by the Abrikosov junction quantum. A memory cell comprising an information reading means having a control line for generating a magnetic field having a magnetic field component parallel to the penetrating magnetic field component. A plurality of memory cells are arranged to form a memory cell array, and the superconductor layer of the information writing means is supplied with a write bit current for selecting a memory cell from the memory cell array and performing writing. It comprises a body layer and a second superconductor layer to which a write word current is supplied.

[Action]

By supplying electric currents in the same direction to the first and second superconductor layers forming the information writing means, a number of Abrikosov magnetic fluxes are internally generated and held in the information storage means. At this time, depending on the direction of the current applied to the first and second superconducting layers, the upward or downward Abrikosov magnetic flux quanta corresponding to "0" or "1" of stored information is selectively applied to the superconducting layer of the information means. Held in. Then, when the control current Ics is applied to the control line and the bias current Is is applied to the Josephson junction element, the Josephson junction element becomes either in the voltage state or the zero voltage state depending on the direction of the Abrikosov magnetic flux quantum.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA '. The information storage means 1 has, as an information storage element, a superconductor layer 2 which internally generates the Abrikosov magnetic flux quantum α when a magnetic field is applied and holds the Abrikosov magnetic flux quantum by itself even after the magnetic field is removed. The superconductor layer 2 is formed, for example, in a rectangular shape or a rectangular shape, and the pair of opposing sides are 3a and 3b, and the other pair of opposing sides are 3c.
And 3d, the stripe-shaped superconductor layers 4a and 4b are extended outward from the side 3c of the sides 3a and 3b and integrally therewith.

The information writing means 11 is supplied with a current,
It has stripe-shaped first superconductor layer 13 and second superconductor layer 12 that generate a magnetic field applied to superconductor layer 2 of information storage means 1 as information writing elements. in this case,
The superconductor layers 12 and 13 are extended along the side 3c of the superconductor layer 2 so as to be juxtaposed with the superconductor layer 2 of the information storage means 1. Further, in FIG. 2 showing the AA ′ cross section of FIG. 1, the superconductor layers 12 and 13 are on the same plane, but in FIG. 1, the superconductor layers 12 and 13 are shown.
The intersections of are also shown. And the superconductor layer 12
It is necessary to supply independent write currents to and 13 as described later. Therefore, although not shown in FIGS. 1 and 2, a step is formed at the intersection of the superconductor layers 12 and 13, and an insulating layer is sandwiched between them to electrically separate the layers. ing.

The information reading means 21 includes a Josephson junction element 22 sensitive to the Abrikosov magnetic flux quantum held by the superconductor layer 2 of the information storage means 1 and a control line 34 for applying a predetermined magnetic field to the Josephson junction element 22. It has as an element for reading information. The Josephson junction element 22 includes a superconductor layer 32 as a lower electrode and a superconductor layer 2 as an upper electrode.
6, and a tunnel barrier layer 25 is interposed between the two. That is, the superconductor layer 32 is formed as a lower electrode on the superconductor layer 2 of the information storage means 1 via the insulating layer 31, and the insulating layer 24 having the window 23 formed on the superconductor layer 32 is formed. A tunnel barrier layer 25 made of, for example, an oxide of the material of the superconductor layer 32 is formed in a region of the superconductor layer 32 that faces the window 23, and a tunnel barrier layer 25 is formed on the insulating layer 24 so as to cover the window 23. The conductor layer 26 is formed as an upper electrode. The control line 34 is composed of a stripe-shaped superconductor layer, and is formed on the superconductor layer 26 via the insulating layer 33 so as to cross over the tunnel barrier layer 25. The Josephson junction element 22 has a magnetic field component parallel to the tunnel barrier layer 25 in the magnetic field by the Abrikosov magnetic flux quantum α as shown by the arrow in FIG. 2, that is, a magnetic field penetrating into the tunnel barrier layer 25 from the left and right direction in FIG. The component is sensed to detect the direction of the Abrikosov magnetic flux quantum α. Therefore, the control 34 is configured to generate a magnetic field having a magnetic field component parallel to the sensing magnetic field component by the Abrikosov magnetic flux quantum α in the tunnel barrier layer 25. Note that T1
T10 indicate each terminal when this device is regarded as one memory cell.

Next, the operation of this embodiment will be described.

When the electric currents IA and IB corresponding to the information "1" are made to flow through the superconductor layers 12 and 13 of the information writing means 11 in the first direction, the information "1" is accordingly transmitted from the superconductor layers 12 and 13. A magnetic field corresponding to “” is generated, and the magnetic field is applied to the superconductor layer 2 of the information storage means 1. Therefore, the Abrikosov magnetic flux quantum α corresponding to the information “1” is internally generated in the first direction (upward “↑”) on the side 3c of the superconductor layer 2 of the information storage means 1. Then, when the application of the magnetic field is continued, the Abrikosov magnetic flux quanta are generated one after another at the side 3c, and the Abrikosov magnetic flux quanta internally generated earlier are pushed into the information reading means 21 side by the repulsive force acting on each other.

At this time, when the current ID is passed through the superconductor layer 2 of the information storage means 1 from the superconductor layer 4b side toward the superconductor layer 4a side (second direction), the information storage means 1 Since the Abrikosov magnetic flux quantum held on the side 3c of the superconductor layer 2 is subjected to the force due to the Lorentz interaction with the current ID and quickly moves to the information reading means 21 side, the writing time can be shortened. Can be planned.

The presence of the relatively thick superconductor layer 32, which is the lower electrode of the Josephson junction element 22, prevents further movement of the Abrikosov magnetic flux quantum that has moved to the information reading means 21 side. In this way, if the Abrikosov magnetic flux quanta intrude into the information storage means 1 and a certain amount or more of the Abrikosov magnetic flux quanta invade, the repulsive force of the Abrikosov magnetic flux quanta makes it difficult to invade them, and the saturated state occurs. . This Abrikosov magnetic flux quantum is the current IA, IE
And when ID is removed, it is self-held by the pinning force of the superconductor layer 2 (the force that captures the Abrikosov magnetic flux quantum).

Next, when the currents IB and IF corresponding to the information "0" are passed through the superconductor layers 12 and 13 of the information writing means 11 in the second direction opposite to the above-mentioned currents IA and IE, the superconductivity is increased. A magnetic field in the direction opposite to the magnetic field corresponding to the above-mentioned information "1" is generated from the body layers 12 and 13, and this magnetic field causes the Abrikosov magnetic flux corresponding to the information "0" in the superconductor layer 2 of the information storage means 1. The quantum is internally generated in the second direction (downward “↓”) opposite to the Abrikosov magnetic flux quantum corresponding to the information “1”. The Abrikosov magnetic flux quantum corresponding to the internally generated information "0" enters like the above-mentioned upward Abrikosov magnetic flux quantum, and is coupled with the upward Abrikosov magnetic flux quantum corresponding to the information "1" that is already self-held. Then disappears. Further, the Abrikosov magnetic flux quanta corresponding to the information "0" penetrates, and finally only the Abrikosov magnetic flux quanta corresponding to the information "0" remains and is retained in the superconductor layer 2 of the information storage means 1. .
This is the holding state of the information “0”. In writing this information "0", a current IC is caused to flow in the first direction from the superconductor layer 4a side to the superconductor layer 4b side in the superconductor layer 2 of the information storage means 1, whereby the information " As in the case of "1" writing, the Abrikosov magnetic flux quantum can be quickly moved from the side 3c side to the Josephson junction element 22 side by Lorentz interaction.

In addition, when writing information, a current is passed through both of the two superconductor layers 12 and 13 in order to selectively write data in a memory cell array in which a plurality of the present device is arranged in a plane as one memory cell. This will be achieved, which will be described in detail after the description of the read operation.

Next, reading of information will be described. To detect the memory state, the control current Ics is passed through the superconductor layer 34 of the information reading means 21, and the predetermined bias region Is is applied to the Josephson junction element 22 of the information reading means 21.
6 through the tunnel barrier layer 25 and the superconductor layer 32. FIG. 3 is a diagram showing the threshold characteristics of the Josephson junction element 22, where the horizontal axis represents the control current value flowing in the control line 34 and the vertical and horizontal axes represent the bias current value flowing in the Josephson junction element 22. In the figure, a broken line 7 is a threshold characteristic curve when the Abrikosov magnetic flux quantum is not held in the information storage means 1, and a solid line 8 is a threshold characteristic curve when the Abrikosov magnetic flux quantum corresponding to the "0" state is held. A solid line 9 is a threshold characteristic curve when the Abrikosov magnetic flux quantum corresponding to the “1” state is held. In this way, the threshold characteristic changes along the horizontal axis depending on the memory state.
This is due to the influence of the magnetic field created by the Abrikosov magnetic flux quantum held in the superconductor layer 2 of the information storage means 1.

Now, the bias current Is is passed through the Josephson junction element 22, and the control current Ics is applied to the control line 34 in the first direction.
The operating point can be moved to the position A by flowing. From the figure, in the “0” state, the operating point A is inside the threshold characteristic curve 8, so the Josephson junction device 2
It can be seen that the state 2 is maintained in the zero voltage state, and if the state is “1”, the operating point A goes out of the threshold characteristic curve 9, so that the state shifts to the voltage state. This phenomenon occurs when the magnetic field created by the downward Abrikosov flux quanta and the magnetic field created by the control current Ics cancel each other in the tunnel barrier layer 25 in the "0" state, and when in the "1" state, It is caused by mutual application of the magnetic field and the magnetic field of the control current Ics. By such an action, the predetermined bias current Is and control current Ics
It is possible to read out whether the storage state is "1" or "0" according to the voltage state of the Josephson junction element 22 when and are simultaneously passed.

Next, selective writing in the memory cell array in which the present device is used as one memory cell will be described.

FIG. 4 is a write characteristic diagram showing the relationship between the transition amount of the threshold characteristic of the Josephson junction device 22 shown in FIG. 3 and the write current. The horizontal axis represents the write current value and the vertical axis represents the transition amount. I am taking it. As described above, the transition amount of the threshold characteristic of the Josephson junction element 22 exhibits a steep rise characteristic and a saturation characteristic symmetrical with respect to the write current with respect to the origin. The steep rise cannot generate Abrikosov magnetic flux quanta in the superconductor layer 2 of the information storage means 1 at a write current below a certain value, and when the current value is exceeded, a large number of Abrikosov magnetic flux quanta are generated. It occurs based on the phenomenon of internal generation and invasion by a group. Further, the saturation characteristic occurs when the Abrikosov magnetic flux quanta intrude to a certain extent or more and the repulsive force between the Abrikosov magnetic flux quanta makes it difficult to invade even if the write current is increased to a certain value or more.

Therefore, for example, when writing information "1", the write current I _W1 applied to the superconductor layers 12 and 13 of the information writing means 11 is set to a value I _W1H or less at which the Abrikosov magnetic flux quantum cannot be internally generated. If it is set to a value such that _{twice the} value is I _W1F which is sufficient to saturate the Abrikosov magnetic flux quantum, the superconductor layer 12 or 13 is set.
The information "1" cannot be stored with either one of the currents, and the information "1" can be stored only when the Abrikosov magnetic flux quantum invades when the current I _W1 is passed through both. Further, the writing of the information "0" can be similarly performed by reversing the direction of the write current.

FIG. 5 shows a structure in which a 4-bit memory cell of 2 rows and 2 columns is configured by using the device of this embodiment as one memory cell. In the figure, AA, AB, BA, and BB are the memory cells in the 1st row, 1st column, 1st row, 2nd column, 2nd row, 1st column, and 2nd row, 2nd column, respectively. Terminal T1 shown
Corresponds to ~ T10. P1 and P1 'are read bit current supply means, P2 and P2' are sense circuits, and P3.
And P3 'are write bit current supply means, P4 and P3.
4'is Lorentz current supply means, P5 and P5 'are write word current supply means, and P6 and P6' are read word current supply means.

The selective write operation of the 4-bit storage cell thus configured is performed as follows. As a specific example, a case of selecting the memory cell AA will be described. Write bit current supply means P
When the above-mentioned write current I _W1 is supplied to the terminal T1 of the memory cell AA from the wiring line W3 from the wiring 3, the write current I _W1 is generated in the superconductor layer 13 which is the information writing means of the memory cells AA and AB. Flowing. At the same time, the terminal T of the memory cell AA from the write word current supply means P5 through the wiring W11.
Supplying write current I _W1 to 3, the write current I _W1 flows in the superconductor layer 12 which is the information writing means of the memory cells AA and memory cells BA. Then, in the memory cell AA, the write current I _W1 flows in both of the superconductor layers 12 and 13, and the information write means 11 has a write current of 2 × I _W1 . Since this current value is set to be equal to or more than the value I _WIF sufficient to saturate the Abrikosov magnetic flux quantum, the information “1” is written. On the other hand, in the memory cell AB, the write current I _W1 flows only in the superconductor layer 13, and in the memory cell BA, the write current I _W1 flows only in the superconductor layer 12.
_W1 flows. Since the write current I _W1 is _{equal to} or less than the value I _WIH at which the Abrikosov magnetic flux quantum cannot be internally generated, the information “1” is not written. In addition, the memory cell BB
Now the two superconductor layers 12 and 1 of the information writing means 11
Since the write current I _W1 is not supplied to either of the three, information is not written. In this way, by selectively driving the write bit current supply means P3 and the write word current supply means P5, selective writing can be performed only on the memory cell AA. Similarly, write bit current supply means P3
When the write word current supply means P5 'is selectively driven, the memory cell AB is selected. When the write bit current supply means P3' and the write word current supply means P5 are selectively driven, the memory cell BA is further added. When the write bit current supply means P3 'and the write word current supply means P5' are selectively driven, the information "1" is written in the memory cell BB. The selective writing of the information "0" can be similarly performed by reversing the direction of the write current I _W1 .

Next, the selective read operation will be described. In the threshold characteristic shown in FIG. 3, the bias current applied to the Josephson junction element 22 of the information reading means 21 overlaps the threshold characteristic curve 9 in the "1" storage state and the threshold characteristic curve 8 in the "0" storage state. Information reading means 2 is set to the value Is of the area.
The control current flowing through the control line 34 of 1 is set to the value Ics of the area within the threshold characteristic curve 8 of the "0" storage state and outside the threshold characteristic curve 9 of the "1" storage state.

Now, assume that the memory cell AA in the 4-bit memory cell of FIG. 5 is selectively read. Read bit current supply means P
When the bias current Is is supplied from 1 to the terminal T7 of the storage cell AA through the wiring W1 and at the same time the control current Ics is supplied from the read word current supply means P6 to the terminal T9 of the storage cell AA through the wiring W9, the Josephson in the storage cell AA. Since the bias current Is is applied to the Son junction element 22 and the control current Ics is applied to the control line 34, the operating point of the threshold characteristic is point A shown in FIG. At this time, when the storage state of the storage cell AA is "1", the operating point A crosses the threshold characteristic curve 9 and goes out of the threshold characteristic curve 9, so that the Josephson junction element 22 changes from the zero voltage state to the voltage state. Transfer. By detecting this voltage by the sense circuit P2, it can be detected that the memory cell AA is in the "1" memory state. Further, when the memory cell AA is in the “0” memory state, the operating point A remains within the threshold characteristic curve 8 of “0”, so that the Josephson junction element 22 is maintained in the zero voltage state. Therefore, the sense circuit P2 does not detect the voltage and can detect that the memory cell AA is in the "0" memory state. At this time, since the bias current Is from the read bit current supply means P1 does not flow in the memory cell BA,
The Josephson junction element 22 never enters the voltage applied state regardless of the stored state. Further, since the control current Ics from the read word current supply means P6 does not flow in the memory cell AB, the operating point is the overlap region between the threshold characteristic curve 9 in the "1" memory state and the threshold curve 8 in the "0" memory state. Therefore, the Josephson junction element 22 is in the zero voltage state regardless of the memory state. Further, since neither the bias current Is nor the control current Ics is supplied to the memory cell BB, the Josephson junction element 22 is in the zero voltage state regardless of the memory state. Therefore, when the read bit current supply means P1 and the read word current supply means P6 are selectively driven, all the memory cells other than the memory cell AA are brought to the zero voltage state regardless of the memory state, and reading can be performed. Absent.

When reading the stored contents of the memory cell BA, the read word current supply means P6 and the read bit current supply means P1 '.
Is driven to detect by the sense circuit P2 ', and the memory cell A
When the stored content of B is read, the read word current supply means P6 'and the read bit current supply means P1 are driven for detection by the sense circuit P2, and when the stored content of the storage cell BB is read, the read word current supply is provided. It suffices to drive the means P6 'and the read bit current supply means P1' and perform detection by the sense circuit P2 '.

If the Lorentz current supply means P4 or P4 'is driven at the time of writing information, the Abrikosov magnetic flux quantum generated internally in the memory cell selected for writing can be moved to the Josephson junction element 22 side at high speed. High-speed writing becomes possible. Further, if the driving is performed at the time of reading information, the distribution of the stored Abrikosov magnetic flux quanta can be changed and a large number of Abrikosov magnetic flux quanta can be accumulated in the vicinity of the Josephson junction element 22, so that the detection sensitivity is improved and a wide margin is obtained. It becomes possible to operate.

In the above embodiment, the sixth junction device is the sixth device.
A single tunnel barrier layer 2 as shown in the conceptual diagram of FIG.
Although the one having 5 is used, a so-called SQUID type having two tunnel barrier layers may be used as shown in FIG. In the figure, 26 and 26 'are upper electrodes, 25 and 25' are tunnel barrier layers, and 32 and 32 '.
Is a lower electrode, and when the SQUID type is used, the threshold characteristic can be changed by configuring the magnetic flux (broken line arrow) by the Abrikosov magnetic flux quantum to cross the central space.

〔The invention's effect〕

As described above, according to the superconducting memory device of the present invention,
"1" is stored in the superconductor layer of the information storage means according to the direction of the current applied to the superconductor layer forming the information writing means.
Alternatively, it is intended to selectively retain the upward or downward Abrikosov magnetic flux quanta corresponding to "0", and whether to hold the upward Abrikosov magnetic flux quanta or to hold the downward Abrikosov magnetic flux quanta. Since the Abrikosov magnetic flux quanta in the memory state before writing are pair annihilated and then written until the saturation state is reached, it is stored at the time of writing like a conventional Abrikosov magnetic flux quantum memory device that uses the presence or absence of the Abrikosov magnetic flux quanta as information elements. It is not necessary to confirm the contents each time and to make pair annihilation of the magnetic flux quanta accurately without excess or deficiency. Therefore, not only the writing operation becomes simple, but also the writing operation margin can be widened. Moreover, there is no malfunction due to accumulation of residual Abrikosov flux quanta.

Further, when the memory cell matrix is configured by using the present device as a memory cell, selective writing can be easily realized because the superconductor layer that constitutes the information writing means is configured by two, and further, the reading can be performed. Since the control current Ics and the bias current Is are used for selection, selective reading can be easily realized.

[Brief description of drawings]

1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA ', FIG. 3 is a view showing threshold characteristics of the Josephson junction element 22, and FIG. 4 is FIG. 5 is a write characteristic diagram showing the relationship between the threshold current transition amount of the Josephson junction element 22 and the write current, and FIG. 5 is a two-row structure in which the embodiment device of FIG. 1 is configured as one memory cell. FIG. 6 is a plan view of a 2-row 4-bit storage cell, FIG. 6 is a perspective view showing the concept of a Josephson junction element, and FIG. 7 is a perspective view showing a conventional Abrikosov magnetic flux quantum storage device. 1 ... Information storage means, 2 ... Superconductor layer, 11 ... Information writing means, 12, 13 ... Superconductor layer, 21 ... Information reading means, 22 ... Josephson junction element, 34 ... … Control lines.

Claims (1)

[Claims] 1. An information storage means having a superconductor layer which internally generates Abrikosov magnetic flux quanta when a magnetic field is applied and self-holds the Abrikosov magnetic flux quanta even in a state where the magnetic field is removed, and information corresponding to information. Information writing means having a superconductor layer for generating a magnetic field applied to the superconductor layer of the information storage means when a current is applied, and self-held in the superconductor layer of the information storage means Generate at least one Josephson junction element sensitive to the magnetic field created by the Abrikosov flux quantum and a magnetic field having a magnetic field component parallel to the magnetic field component that penetrates the tunnel barrier layer of the Josephson junction device among the magnetic fields generated by the Abrikosov flux quantum A plurality of memory cells each including an information reading means having a control line for forming a memory cell array. The superconductor layer of the data writing means has a write word current and a first superconductor layer to which a write bit current for selecting the memory cell from the memory cell array and performing writing is supplied. A superconducting memory device comprising a supplied second superconductor layer.