Magnetic josephson junction driven flux-biased superconductor memory cell and methods

1. A memory cell comprising:

a magnetic Josephson junction (MJJ) superconducting quantum interference device (SQUID) comprising a first MJJ device and a second MJJ device, arranged in parallel to each other, wherein the MJJ SQUID is configured to generate a first flux-bias or a second flux-bias, wherein the first flux-bias corresponds to a first direction of current flow in the MJJ SQUID and the second flux-bias corresponds to a second direction of current flow in the MJJ SQUID, wherein the first direction is opposite to the second direction; and

a superconducting metal-based superconducting quantum interference device (SQUID) including a first Josephson junction (JJ) and a second JJ, arranged in parallel to each other, wherein each of the first JJ and the second JJ has a critical current responsive to any flux-bias generated by the MJJ SQUID, and wherein in response to a read operation, the superconducting metal-based SQUID is configured to provide an output based at least on the first flux-bias or the second flux-bias.

2. The memory cell of claim 1 , wherein the first flux-bias corresponds to a first logic state of the memory cell and the second flux-bias corresponds to a second logic state of the memory cell, wherein the second logic state is opposite to the first logic state.

3. The memory cell of claim 2 , wherein the output comprises a voltage pulse when a logic state of the memory cell is the first logic state and wherein the output comprises no voltage pulse when a logic state of the memory cell is the second logic state.

4. The memory cell of claim 2 , wherein each of the first MJJ device and the second MJJ device comprises a first layer formed above a second layer and a third layer formed below the second layer, wherein the first layer is a free magnetic layer, the second layer is a non-magnetic layer, and wherein the third layer is a fixed magnetic layer.

5. The memory cell of claim 4 , wherein the first logic state corresponds to a first configuration of magnetization of the free magnetic layer and the second logic state corresponds to a second configuration of magnetization of the free magnetic layer, wherein the first configuration of the magnetization of the free magnetic layer corresponds to a first magnetic field that is parallel to a magnetic field of the fixed magnetic layer and the second configuration of the magnetization of the free magnetic layer corresponds to a second magnetic field that is anti-parallel to the magnetic field of the fixed magnetic layer.

6. The memory cell of claim 1 , wherein each of the first MJJ device and the second MJJ device comprises a first superconducting metal layer, a dielectric layer, an anti-ferromagnetic layer, a conductive metal layer, a ferromagnetic layer, and a second superconducting metal layer.

7. The memory cell of claim 1 , wherein each of the first MJJ device and the second MJJ device is configured for single-domain switching.

8. A method in a memory cell including a magnetic Josephson junction (MJJ) superconducting quantum interference device (SQUID) comprising a first MJJ device and a second MJJ device, arranged in parallel to each other, and a superconducting metal-based superconducting quantum interference device (SQUID) including a first Josephson junction (JJ) and a second JJ, arranged in parallel to each other, the method comprising:

generating a first flux-bias or a second flux-bias, wherein the first flux-bias corresponds to a first direction of current flow in the MJJ SQUID and the second flux-bias corresponds to a second direction of current flow in the MJJ SQUID, wherein the first direction is opposite to the second direction; and

in response to a read operation, responsive to any flux-bias generated by the MJJ SQUID, the superconducting metal-based SQUID providing an output based at least on the first flux-bias or the second flux-bias.

9. The method of claim 8 , wherein the first flux-bias corresponds to a first logic state of the memory cell and the second flux-bias corresponds to a second logic state of the memory cell, wherein the second logic state is opposite to the first logic state.

10. The method of claim 9 , wherein the output comprises a voltage pulse when a logic state of the memory cell is the first logic state and wherein the output comprises no voltage pulse when a logic state of the memory cell is the second logic state.

11. The method of claim 9 , wherein each of the first MJJ device and the second MJJ device comprises a first layer formed above a second layer and a third layer formed below the second layer, wherein the first layer is a free magnetic layer, the second layer is a non-magnetic layer, and wherein the third layer is a fixed magnetic layer.

12. The method of claim 11 , wherein the first logic state corresponds to a first configuration of magnetization of the free magnetic layer and the second logic state corresponds to a second configuration of magnetization of the free magnetic layer, wherein the first configuration of the magnetization of the free magnetic layer corresponds to a first magnetic field that is parallel to a magnetic field of the fixed magnetic layer and the second configuration of the magnetization of the free magnetic layer corresponds to a second magnetic field that is anti-parallel to the magnetic field of the fixed magnetic layer.

13. The method of claim 8 , wherein each of the first MJJ device and the second MJJ device comprises a first superconducting metal layer, a dielectric layer, an anti-ferromagnetic layer, a conductive metal layer, a ferromagnetic layer, and a second superconducting metal layer.

14. The method of claim 8 , wherein each of the first MJJ device and the second MJJ device is configured for single-domain switching.

15. A memory system comprising:

an array of memory cells arranged in rows and columns;

a set of read word-lines coupled to the array of the memory cells;

a set of read bit-lines coupled to the array of memory cells, and wherein each of the memory cells comprises:

a magnetic Josephson junction (MJJ) superconducting quantum interference device (SQUID) comprising a first MJJ device and a second MJJ device, arranged in parallel to each other, wherein the MJJ SQUID is configured to generate a first flux-bias or a second flux-bias, wherein the first flux-bias corresponds to a first direction of current flow in the MJJ SQUID and the second flux-bias corresponds to a second direction of current flow in the MJJ SQUID, wherein the first direction is opposite to the second direction; and

a superconducting metal-based superconducting quantum interference device (SQUID) including a first Josephson junction (JJ) and a second JJ, arranged in parallel to each other, wherein each of the first JJ and the second JJ has a critical current responsive to any flux-bias generated by the MJJ SQUID, and wherein in response to a read operation initiated via at least one of set of the read word-lines and at least one of the set of the read-bit lines, the superconducting metal-based SQUID is configured to provide an output based at least on the first flux-bias or the second flux-bias.

16. The memory system of claim 15 , wherein the first flux-bias corresponds to a first logic state of the memory cell and the second flux-bias corresponds to a second logic state of the memory cell, and wherein the second logic state is opposite to the first logic state.

17. The memory system of claim 16 , wherein the output comprises a voltage pulse when a logic state of the memory cell is the first logic state and wherein the output comprises no voltage pulse when a logic state of the memory cell is the second logic state.

18. The memory system of claim 16 , wherein each of the first MJJ device and the second MJJ device comprises a first layer formed above a second layer and a third layer formed below the second layer, wherein the first layer is a free magnetic layer, the second layer is a non-magnetic layer, and wherein the third layer is a fixed magnetic layer.

19. The memory system of claim 18 , wherein the first logic state corresponds to a first configuration of magnetization of the free magnetic layer and the second logic state corresponds to a second configuration of magnetization of the free magnetic layer, wherein the first configuration of the magnetization of the free magnetic layer corresponds to a first magnetic field that is parallel to a magnetic field of the fixed magnetic layer and the second configuration of the magnetization of the free magnetic layer corresponds to a second magnetic field that is anti-parallel to the magnetic field of the fixed magnetic layer.

20. The memory system of claim 15 , wherein each of the first MJJ device and the second MJJ device comprises a first superconducting metal layer, a dielectric layer, an anti-ferromagnetic layer, a conductive metal layer, a ferromagnetic layer, and a second superconducting metal layer.