Versatile spin-polarized electron source
One or more embodiments relate generally to the field of photoelectron spin and, more specifically, to a method and system for creating a controllable spin-polarized electron source. One preferred embodiment of the invention generally comprises: method for creating a controllable spin-polarized electron source comprising the following steps: providing one or more materials, the one or more materials having at least one surface and a material layer adjacent to said surface, wherein said surface comprises highly spin-polarized surface electrons, wherein the direction and spin of the surface electrons are locked together; providing at least one incident light capable of stimulating photoemission of said surface electrons; wherein the photon polarization of said incident light is tunable; and inducing photoemission of the surface electron states.
1. A method of creating a controllable spin-polarized electron source comprising the following steps:
a. providing one or more materials, the one or more materials having at least one surface and a material layer adjacent to said surface, wherein said surface comprises highly spin polarized surface electrons, wherein the direction and spin of the surface electrons are locked together;
b. providing at least one incident light capable of stimulating photoemission of said surface electrons: wherein the incident light has a photon energy above the work function of said materials; wherein the photon polarization of incident light is tunable; wherein the different polarization and orientation of the incident light result in different polarization of said surface electrons; and
c. inducing photoemission of the surface electron states.
2. The method of claim 1 , wherein the photon polarization is linearly polarized light.
3. The method of claim 1 , wherein the photon polarization is normally incident circularly polarized photons.
4. The method of claim 1 , wherein said linear polarization of the light is rotated about the light propagation axis up to 360°.
5. The method of claim 4 , wherein the photon polarization is p-polarized resulting in an intensity peak of photoelectrons of a defined polarization determined by the angle of emission.
6. The method of claim 4 , wherein the photon polarization is s-polarized resulting in an intensity peak of photoelectrons of a defined polarization determined by the angle of emission; wherein the defined polarization is opposite to an intensity peak from p-polarized photon polarization at the same angle of emission.
7. The method of claim 4 , wherein the photon polarization vector is rotated to +45° or halfway between p- and s-polarizations.
8. The method of claim 4 , wherein the photon polarization vector is rotated to −45 ° resulting in photoelectron spin polarization.
9. The method of claim 5 , wherein the circularly polarized photon source is right-hand circularly polarized light; wherein when the right-hand circularly polarized light is incident along the surface normal resulting in spins directed into the surface plane of the material perpendicularly and a negative polarization.
10. The method of claim 5 , wherein the circularly polarized photon source is left-hand circularly polarized light; wherein when the left-hand circularly polarized light is incident along the surface normal resulting in spins directed away from the surface plane of the material perpendicularly and a positive polarization.
11. The method of claim 4 , wherein step of collecting said emitted photoelectrons is done by way of an electron extractor at a given emission angle.
12. The method of claim 11 , wherein said linearly polarized light is at a fixed orientation.
13. The method of claim 12 , wherein said emitted photoelectrons perfectly perpendicular to the surface is defined as zero degrees (0°); said photoelectrons emitted at 0° have zero spin polarization; the emitted photoelectrons collected by said extractor are at an emission polar angle other than 0°; wherein said emission polar angle of surface state extends from greater than 0° to 90°; wherein said emission azimuthal angles can vary from 0° to 360°; and photoelectrons emitted along opposite azimuthal angles separated by 180° have opposite spin polarizations.
14. The method of creating a controllable spin-polarized electron source of claim 1 , wherein:
a. said one or more materials is selected from the group of three-dimensional topological insulators including, but not limited to: bismuth antimonide, antimony, bismuth selenide, bismuth telluride, antimony telluride, samarium hexaboride, and stanene;
b. wherein the photon polarization is linearly polarized light.
15. The method of claim 14 , wherein said linear polarization of the light is rotated about the light propagation axis up to 180°.
16. The method of claim 14 , wherein the photon polarization is p-polarized resulting in an intensity peak of photoelectrons of a defined polarization determined by the angle of emission.
17. The method of claim 14 , wherein the photon polarization is s-polarized resulting in an intensity peak of photoelectrons of a defined polarization determined by the angle of emission; wherein the defined, polarization is opposite to an intensity peak from p-polarized photon polarization at the same angle of emission.
18. The method of claim 14 , wherein the photon polarization vector is rotated to +45° or halfway between p- and s-polarizations.
19. The method of claim 14 , wherein the photon polarization vector is rotated to −45° resulting in photoelectron spin polarization.
20. The method of creating a controllable spin-polarized electron source of claim 1 , wherein:
a. said one or more materials is selected from the group of three-dimensional topological insulators including, but not limited to: bismuth antimonide, antimony, bismuth selenide, bismuth telluride, antimony telluride, samarium hexaboride, and stanene;
b. wherein the photon polarization is normally incident circularly polarized photons.
21. The method of claim 20 , wherein the circularly polarized photon source is right-hand circularly polarized light; wherein when the right-hand circularly polarized light is incident along the surface normal resulting in spins directed into the surface plane of the material perpendicularly and a negative polarization.
22. The method of claim 20 , wherein the circularly polarized photon source is left-hand circularly polarized light; wherein when the right-hand circularly polarized light is incident along the surface normal resulting in spins directed into the surface plane of the material perpendicularly and a negative polarization.
23. The method of claim 14 , comprising a step of collecting said emitted photoelectrons carried out by way of an electron extractor at a given emission angle.
24. The method of claim 23 , wherein said linearly polarized light is at a fixed orientation.
25. The method of claim 24 , wherein said emitted photoelectrons perfectly perpendicular to the surface is defined as zero degrees (0°); said photoelectrons emitted at 0° have zero spin polarization; the emitted photoelectrons collected by said extractor are at an emission polar angle other than 0°; wherein said emission polar angle of surface state extends from greater than 0° to 90°; wherein said emission azimuthal angles can vary from 0 to 360°; and photoelectrons emitted along opposite azimuthal angles separated by 180° have opposite spin polarizations.