1. A cart comprising a rotor (9, 7) arranged to cooperate with a stator (7, 9) arranged in the ground, such that they conjointly constitute a dynamoelectric machine, characterised in that said rotor (9, 7) is provided with an essentially flat lower surface arranged on the cart near the ground surface.
2. A cart according to claim 1, characterised in that it comprises an accumulator (6).
3. A cart according to claim 1, characterised in that it comprises an outlet (3, 4) for drawing electrical power from the dynamoelectric machine andor the accumulator (6).
4. A cart according to claim 2, characterised in that it comprises an outlet (3, 4) for drawing electrical power from the dynamoelectric machine andor the accumulator (6).
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for noncontact writing of a magnetic bit, comprising:
providing a plurality of magnetic islands on a nonmagnetic layer;
providing a reference layer under the nonmagnetic layer; and
causing a spin-current to write a state to a magnetic island of the plurality of magnetic islands by moving a heat source to create a temperature gradient throughout the magnetic island and the reference layer.
2. The method of claim 1, wherein causing the spin-current to write the state to the magnetic island of the plurality of magnetic islands by moving the heat source to create a temperature gradient throughout the magnetic island and the reference layer comprises: heating the magnetic island to cause the thermal gradient across the magnetic island, the nonmagnetic layer, and the reference layer; and
wherein at least one of: the spin-current writes the state of the magnetic island to be parallel to the reference layer, and the spin-current writes the state of the magnetic island to be antiparallel to the reference layer.
3. The method of claim 2, wherein a temperature of the magnetic island is greater than a temperature of the reference layer as a result of the thermal gradient.
4. The method of claim 1, wherein the state of the magnetic island is a one or zero; and
wherein the magnetic island is a magnetic bit.
5. The method of claim 1, wherein the magnetic island has a first moment and the reference layer has a second moment;
wherein the spin-current induced in the reference layer causes the first moment to be parallel to the second moment; and
wherein the first moment corresponds to the state of the magnetic island.
6. The method of claim 1, further comprising when a plurality of moments of the plurality magnetic islands are written to be parallel to a moment of the reference layer, flipping the moment of the reference layer to be antiparallel to the plurality of moments of the plurality of magnetic islands.
7. The method of claim 6, wherein flipping the moment of the reference layer to be antiparallel to the plurality of moments of the plurality of magnetic islands comprises a reset head generating a magnetic field that flips the moment of the reference layer; and
wherein a magnitude of the magnetic field that flips the moment of the reference layer is not high enough to flip any of the plurality of moments of the plurality of magnetic islands.
8. The method of claim 6, wherein flipping the moment of the reference layer to be antiparallel to the plurality of moments of the plurality of magnetic islands comprises a reset head generating a magnetic field that flips the moment of the reference layer; and
wherein a magnitude of the magnetic field that flips the moment of the reference layer is sufficient to also flip any of the plurality of moments of the plurality of magnetic islands.
9. The method of claim 1, further comprising aligning a plurality of moments of the plurality of magnetic islands to a direction; and
writing as a group to the plurality of magnetic islands by heating the plurality of magnetic islands to cause respective spin-currents to change the direction of the plurality of moments to an opposite direction.
10. The method of claim 1, wherein the heat source is a near-field optical source that generates a near-field optical beam, in which the near-field optical beam can heat any of the plurality of magnetic islands.
11. The method of claim 1, wherein the plurality of magnetic islands are physically separated structures; or
wherein the plurality of magnetic islands are magnetic domains inside a continuous magnetic film in which the magnetic domains are suitable for sustaining a distinct and stable magnetic state.
12. An apparatus for noncontact writing, comprising:
a plurality of magnetic islands on a nonmagnetic layer;
a reference layer under the nonmagnetic layer; and
a write head comprising a heat source, the write head is configured to cause a spin-current to write a state to a magnetic island of the plurality of magnetic islands by moving the heat source to create a temperature gradient throughout the magnetic island and the reference layer.
13. The apparatus of claim 12, wherein the write head is configured to cause the spin-current to write the state to the magnetic island of the plurality of magnetic islands by moving the heat source to create the temperature gradient throughout the magnetic island and the reference layer comprises: the write head being configured to heat the magnetic island to cause the thermal gradient across the magnetic island, the nonmagnetic layer, and the reference layer; and
wherein the spin-current aligns the state of the magnetic island to be parallel to the reference layer.
14. The apparatus of claim 13, wherein a temperature of the magnetic island is greater than a temperature of the reference layer.
15. The apparatus of claim 12, wherein the state of the magnetic island is a one or zero; and
wherein the magnetic island is a magnetic bit.
16. The apparatus of claim 12, wherein the magnetic island has a first moment and the reference layer has a second moment;
wherein the spin-current induced in the reference layer causes the first moment to be parallel to the second moment; and
wherein the first moment corresponds to the state of the magnetic island.
17. The apparatus of claim 12, further comprising a reset head;
wherein when a plurality of moments of the plurality magnetic islands are written to be parallel to a moment of the reference layer, the reset head is configured to flip the moment of the reference layer to be antiparallel to the plurality of moments of the plurality of magnetic islands.
18. The apparatus of claim 17, wherein the reset head is configured to generate a magnetic field that flips the moment of the reference layer; and
wherein a magnitude of the magnetic field that flips the moment of the reference layer is not high enough to flip any of the plurality of moments of the plurality of magnetic islands.
19. The apparatus of claim 17, wherein the reset head is configured to generate a magnetic field that flips the moment of the reference layer; and
wherein a magnitude of the magnetic field that flips the moment of the reference layer is also high enough to flip any of the plurality of moments of the plurality of magnetic islands.
20. The apparatus of claim 12, wherein the write head is configured to align a plurality of moments of the plurality of magnetic islands to a direction; and
wherein when writing as a group to the plurality of magnetic islands, the write head is configured to heat the plurality of magnetic islands to cause respective spin-currents to change the direction of the plurality of moments.
21. The apparatus of claim 12, wherein the heat source is a near-field optical source that generates a near-field optical beam, in which the near-field optical beam can heat any of the plurality of magnetic islands.
22. The apparatus of claim 12, wherein the plurality of magnetic islands are physically separated structures; or
wherein the plurality of magnetic islands are magnetic domains inside a continuous magnetic film in which the magnetic domains are suitable for sustaining a distinct and stable magnetic state.
23. A computer program product for noncontact writing, comprising a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:
utilizing a plurality of magnetic islands on a nonmagnetic layer;
utilizing a reference layer under the nonmagnetic layer; and
causing a spin-current to write a state to a magnetic island of the plurality of magnetic islands by moving a heat source to create a temperature gradient throughout the magnetic island and the reference layer.
24. The computer program product of claim 23, wherein causing the spin-current to write the state to the magnetic island of the plurality of magnetic islands by moving the heat source to create the temperature gradient throughout the magnetic island and the reference layer comprises: heating the magnetic island to cause the thermal gradient across the magnetic island, the nonmagnetic layer, and the reference layer; and
wherein the spin-current writes the state of the magnetic island to be parallel to the reference layer.