Single-charge tunnelling device
AssigneeHitachi, Ltd.
InventorsJörg Wunderlich, David Williams, Tomas Jungwirth, Andrew Irvine, Bryan Gallagher
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Abstract
A single-electron transistor (1) has an elongate conductive channel (2) and a side gate (3) formed in a 5 nm-thick layer (4) of Ga0.98Mn0.02As. The single-electron transistor (1) is operable, in a first mode, as a transistor and, in a second mode, as non-volatile memory.
Claims25
A magnetoresistance single-charge tunnelling device comprising:
- first and second leads;
- a conductive island having a charging energy of at least 1 meV and arranged such that charge is transferable from the first lead to the second lead via the conductive island;
- and
- a gate for changing an electrostatic energy of the conductive island;
- and
- wherein at least one of said first lead, second lead, island and the gate comprises a ferromagnetic material which exhibits strong spin-orbit coupling such that the at least one of the said first lead, second lead, island and the gate exhibits a change in chemical potential of at least an order of the charging energy in response to rotation of magnetization from a first orientation to a second orientation which is not parallel or anti-parallel to the first orientation, wherein neither the first and second leads provide a pinned region;
- and wherein
- the single-charge tunneling device exhibits an anisotropic magnetoresistance effect and not a tunneling magnetoresistance effect wherein the first lead, the second lead and the island each comprise the same ferromagnetic material.
A magnetoresistance single-charge tunnelling device comprising:
- first and second leads;
- and
- a conductive island having a charging energy of at least 1 meV and arranged such that charge is transferable from the first lead to the second lead via the conductive island;
- and
- wherein at least one of the first lead, second lead and island comprises a ferromagnetic material which exhibits strong spin-orbit coupling such that the at least one of the said first lead, second lead and island exhibits a change in chemical potential of at least an order of the charging energy in response to rotation of magnetization from a first orientation to a second orientation which is not parallel or anti-parallel to the first orientation;
- wherein neither the first and second leads provide a pinned region;
- and wherein the single-charge tunneling device exhibits an anisotropic magnetoresistance effect and not a tunneling magnetoresistance effect wherein the first lead, the second lead and the island each comprise the same ferromagnetic material.
A magnetoresistance device comprising:
- first and second leads;
- first and second tunnel barriers;
- and
- a conductive island having a charging energy of at least 1 meV and arranged such that charge is transferable from the first lead to the second lead via the first tunnel barrier, the conductive island and the second tunnel barrier;
- and
- wherein at least one of the first lead, second lead and island comprises a ferromagnetic material which exhibits strong spin-orbit coupling such that the at least one of the said first lead, second lead and island exhibits a change in chemical potential of at least an order of the charging energy in response to rotation of magnetization from a first orientation to a second orientation which is not parallel or anti-parallel to the first orientation, wherein neither the first and second leads provide a pinned region and wherein the device exhibits an anisotropic magnetoresistance effect and not a tunneling magnetoresistance effect wherein the first lead, the second lead and the island each comprise the same ferromagnetic material.
A method of operating a single-charge tunnelling device comprising first and second leads, a conductive island having a charging energy of at least 1 meV and arranged such that charge is transferable from the first lead to the second lead via the conductive island and a gate for changing an electrostatic energy of the conductive island, at least one of said first lead, second lead, island and the gate comprises a ferromagnetic material which exhibits strong spin-orbit coupling such that the at least one of the said first lead, second lead, island and the gate exhibits a change in chemical potential of at least an order of the charging energy in response to rotation of magnetization from a first orientation to a second orientation which is not parallel or anti-parallel to the first orientation, wherein neither the first and second leads provide a pinned region and wherein the single-charge tunneling device exhibits an anisotropic magnetoresistance effect and not a tunneling magnetoresistance effect wherein the first lead, the second lead and the island each comprise the same ferromagnetic material, the method comprising:
- applying a first bias to the gate;
- removing said first bias from the gate;
- measuring a first resistance between the leads;
- applying a second, different bias to the gate;
- removing said second bias from the gate;
- and
- measuring a second resistance between the leads such that the first and second resistances differ.
A method of operating a single-charge tunnelling device comprising first and second leads, a conductive island having a charging energy of at least 1 meV and arranged such that charge is transferable from the first lead to the second lead via the conductive island, at least one of said first lead, second lead and island comprises a ferromagnetic material which exhibits strong spin-orbit coupling such that the at least one of said first lead, second lead, island and the gate exhibits a change in chemical potential of at least an order of the charging energy in response to rotation of magnetization from a first orientation to a second orientation which is not parallel or anti-parallel to the first orientation, neither the first and second leads provide a pair of free and pinned regions and wherein the single-charge tunneling device exhibits an anisotropic magnetoresistance effect and not a tunneling magnetoresistance effect wherein the first lead, the second lead and the island each comprise the same ferromagnetic material, the method comprising:
- applying a first magnetic field;
- removing the first magnetic field;
- measuring a first resistance between the leads;
- applying a second, different magnetic field;
- removing the second magnetic field;
- and
- measuring a second resistance between the leads such that the first and second resistances differ.
Dependencies are inferred from the claim text.