Switchable superconducting Josephson junction device for low energy information storage and processing

A switchable Josephson junction comprising:

• a plurality of ferromagnetic insulators that are defined by their respective magnetic alignments;
• a first superconducting layer that is positioned between any two of the ferromagnetic insulators, wherein the conductive state is controlled by the relative magnetization orientation of the ferromagnetic insulators where the first superconducting layer is superconducting when the two magnetizations are aligned in antiparallel but it turns normally conducting when the magnetic alignment is parallel;
• and
• a second superconducting layer that is positioned between any two of the ferromagnetic layers, wherein Josephson tunneling occurs between the first superconducting layer and second superconducting layer across one of the ferromagnetic layers.

A method of forming an exchange field junction comprising:

• providing a plurality of ferromagnetic insulators that are defined by their respective magnetic alignments;
• positioning a first superconducting layer between any two of the ferromagnetic insulators;
• and
• positioning a second superconducting layer so that it is positioned between any two of the ferromagnetic layers, wherein Josephson tunneling occurs between the first superconducting layer and second superconducting layer across one of the ferromagnetic layers having a magnetic alignment that is antiparrellel relative to the other, wherein the magnetic alignment is controlled by the conducting state of the first superconducting layer.

A switchable Josephson junction comprising:

• a plurality of ferromagnetic insulators that are defined by their respective magnetic alignments;
• a first superconducting layer that is positioned between any two of the ferromagnetic insulators, wherein the conductive state is controlled by the relative magnetization orientation of the neighboring ferromagnetic insulators where the first superconducting layer is superconducting when the two magnetization are aligned in antiparallel but it turns normally conducting when the two magnetization are parallel;
• and
• a second superconducting layer that is positioned between any two of the ferromagnetic insulators, wherein the conductive state is controlled by the relative magnetization orientation of the neighboring ferromagnetic insulators where the second superconducting layer is superconducting when the two magnetization are aligned in antiparallel but it turns normally conducting when the two magnetization are parallel,
• wherein Josephson tunneling is controlled by relative magnetic alignment of the three ferromagnetic insulators occurs between the first superconducting layer and second superconducting layer when they are superconducting states across the ferromagnetic layers positioned between the first superconducting layer and second superconducting layer, wherein the tunneling behavior have four states depending on the relative magnetization orientation.

A method of forming an exchange field junction comprising:

• providing a plurality of ferromagnetic insulators that are defined by their respective magnetic alignments;
• positioning a first superconducting layer between any two of the ferromagnetic insulators;
• and
• positioning a second superconducting layer so that it is positioned between any two of the ferromagnetic insulators, wherein Josephson tunneling occurs between the first superconducting layer and second superconducting layer across the ferromagnetic layers positioned between the first superconducting layer and second superconducting layer where the ferromagnetic layers have magnetic alignments that are not all the same,
• wherein the magnetic alignments are controlled by the conducting state of the first superconducting layer and second superconducting layer.

A switchable Josephson junction comprising:

• a junction that comprises at one least ferromagnetic insulator;
• and
• a first topological insulator (TI) layer positioned on the junction
• a first high atomic number (Z) layer or a bilayer that comprises a second TI layer and a plurality of second high Z layers that is adjacent to the at least one ferromagnetic insulator;
• and
• a dielectric layer that is placed on the first TI layer or the first high Z layer, or the bilayer;
• and
• a metal electrode adjacent to the dielectric layer, wherein the magnetization of the at least one ferromagnetic insulator is switched by applying a gate voltage between the first TI layer or first high Z layer or the bilayer and the metal electrode, the gate voltage tunes the chemical potential of the first TI layer and/or the first high Z layer to change the interface properties between the at least one ferromagnetic layer and the TI layer or the first high Z layer via spin orbit coupling, and thus can cause magnetization switching of the ferromagnetic insulator.