Magnetic memory device and operation method thereof

1. A magnetic memory device, comprising:

a first magnetic memory device;

a second magnetic memory device connected to the first magnetic memory device;

a pulse power supplying current pulses to the first and second magnetic memory devices; and

a switch configured to selectively connect the pulse power to one of the first and second magnetic memory devices,

wherein each of the first and second magnetic memory devices comprises a first fixed layer, a first non-magnetic layer, a free layer, a second non-magnetic layer, and a second fixed layer, which are sequentially stacked, the first fixed layer having a magnetization direction maintained in a fixed direction, the free layer having a perpendicular magnetic anisotropy and a variable magnetization direction, the second fixed layer having a magnetization direction maintained in an opposite direction of the first fixed layer, and

a resistance value of an MTJ device composed of the first fixed layer, the first non-magnetic layer, and the free layer is different from a resistance value of an MTJ device composed of the second fixed layer, the second non-magnetic layer, and the free layer.

2. The magnetic memory device of claim 1 , further comprising a pulse counter which is used to count the number of the current pulses supplied from the pulse power.

3. The magnetic memory device of claim 2 , wherein each of the first and second magnetic memory devices comprises two or more memory devices connected in series.

4. The magnetic memory device of claim 2 , wherein the second fixed layer of the first magnetic memory device is connected to the second fixed layer of the second magnetic memory device,

one of two outputs of the pulse power is connected to the first fixed layer of the first magnetic memory device, and

the switch is configured to change connection of the pulse power such that the other of the two outputs of the pulse power is connected to the second fixed layer of the first magnetic memory device or the first fixed layer of the second magnetic memory device.

5. The magnetic memory device of claim 4 , wherein each of the first and second magnetic memory devices comprises two or more memory devices connected in series.

6. The magnetic memory device of claim 4 , wherein, when a data reading operation on the magnetic memory device is performed, the other of the two outputs of the pulse power is switched to be connected to the first fixed layer of the second magnetic memory device by the switch,

the data reading operation comprises a first reading operation and a second reading operation which are alternately performed, and

the pulse power produces current pulses flowing in opposite directions, in the first and second reading operations.

7. The magnetic memory device of claim 6 , wherein each of the first and second magnetic memory devices comprises two or more memory devices connected in series.

8. The magnetic memory device of claim 6 , wherein the other of the two outputs of the pulse power is switched to be connected to the first fixed layer of the second magnetic memory device by the switch, when a data erase operation on the magnetic memory device is performed, and

the other of the two outputs of the pulse power is switched to be connected to the second fixed layer of the first magnetic memory device by the switch, when a data write operation on the magnetic memory device is performed.

9. The magnetic memory device of claim 8 , wherein each of the first and second magnetic memory devices comprises two or more memory devices connected in series.

10. The magnetic memory device of claim 1 , wherein each of the first and second magnetic memory devices comprises two or more memory devices connected in series.

11. The magnetic memory device of claim 1 , wherein the magnetic memory device is used to write a coupling weight value of a neural network.

12. The magnetic memory device of claim 1 , wherein the magnetic memory device is used to write a weight of a reservoir calculation model.

13. The magnetic memory device of claim 1 , wherein the second fixed layer of the first magnetic memory device is connected to the second fixed layer of the second magnetic memory device,

one of two outputs of the pulse power is connected to the first fixed layer of the first magnetic memory device, and

the switch is configured to change connection of the pulse power such that the other of the two outputs of the pulse power is connected to the second fixed layer of the first magnetic memory device or the first fixed layer of the second magnetic memory device.

14. The magnetic memory device of claim 13 , wherein, when a data reading operation on the magnetic memory device is performed, the other of the two outputs of the pulse power is switched to be connected to the first fixed layer of the second magnetic memory device by the switch,

the data reading operation comprises a first reading operation and a second reading operation which are alternately performed, and

the pulse power produces current pulses flowing in opposite directions, in the first and second reading operations.

15. The magnetic memory device of claim 14 , wherein the other of the two outputs of the pulse power is switched to be connected to the first fixed layer of the second magnetic memory device by the switch, when a data erase operation on the magnetic memory device is performed, and

the other of the two outputs of the pulse power is switched to be connected to the second fixed layer of the first magnetic memory device by the switch, when a data write operation on the magnetic memory device is performed.

16. A method of operating a magnetic memory device, wherein the magnetic memory device comprises a first magnetic memory device and a second magnetic memory device connected to the first magnetic memory device,

each of the first and second magnetic memory devices comprises a first fixed layer, a first non-magnetic layer, a free layer, a second non-magnetic layer, and a second fixed layer, which are sequentially stacked, the first fixed layer having a magnetization direction maintained in a fixed direction, the free layer having a perpendicular magnetic anisotropy and a variable magnetization direction, the second fixed layer having a magnetization direction maintained in an opposite direction of the first fixed layer, and

a resistance value of an MTJ device composed of the first fixed layer, the first non-magnetic layer, and the free layer is different from a resistance value of an MTJ device composed of the second fixed layer, the second non-magnetic layer, and the free layer,

wherein the method of operating the magnetic memory device comprises:

a first reading step supplying driving pulses to the first and second magnetic memory devices until the entirety of the free layer of the first magnetic memory device has the same magnetization direction, thereby transferring a data value, which is written in the free layer of the first magnetic memory device, to the free layer of the second magnetic memory device; and

a second reading step supplying driving pulses to the first and second magnetic memory devices until the entirety of the free layer of the second magnetic memory device has the same magnetization direction, thereby transferring a data value, which is written in the free layer of the second magnetic memory device, to the free layer of the first magnetic memory device.

17. The method of claim 16 , before the first reading step and the second reading step, further comprising,

an erase step supplying driving pulses to the first and second magnetic memory devices such that the entirety of the free layer of the first magnetic memory device has the same magnetization direction and the entirety of the free layer of the second magnetic memory device has the same magnetization direction; and

a write step supplying current pulses whose number is given based on a data value to be written to the first magnetic memory device to change the magnetization direction of the free layer of the first magnetic memory device.

18. The method of claim 17 , wherein the first reading step and the second reading step are performed in an alternate manner.

19. The method of claim 16 , wherein the first reading step and the second reading step are performed in an alternate manner.