Electron beam source and method of manufacturing the same

1. A source, comprising:

a base;

a tip fixed to the base and extending from the base, the tip comprising:

a core having a surface comprising a first material; and

a coating on the core, the coating comprising a second material, the second material forming a surface of the tip, and the second material comprising more than 30% by weight of a lanthanide element;

a first electrical terminal electrically connected to the coating;

an extraction electrode having an opening; and

a second electrical terminal electrically connected to the extraction electrode,

wherein:

the source is an electron beam source, and the first material is different from the second material; and

at least one of the following conditions is fulfilled:

an electrical conductivity of the first material is less than 10 5 S/m; and

a ratio of the electrical conductivity of the second material to the electrical conductivity of the first material is greater than 10:1.

2. The source according to claim 1 , wherein the lanthanide element comprises Gadolinium.

3. The source according to claim 1 , wherein the second material consists essentially of Gadolinium.

4. The source according to claim 1 , wherein the second material comprises at least two different lanthanide elements.

5. The source according to claim 1 , further comprising a magnet configured to generate a magnetic field at the tip.

6. The source according to claim 5 , wherein the magnet comprises a coil having a bore, and the tip is located within the bore of the coil.

7. The source according to claim 1 , further comprising a cooler.

8. The source according to claim 7 , wherein the cooler comprises a Peltier element.

9. A system comprising:

a source according to claim 1 ;

a lens configured to focus a beam of electrons generated by the source in a sample plane; and

at least one electron detector.

10. The system according to claim 9 , wherein the system comprises at least one pair of detectors symmetrically arranged relative to an axis of symmetry of the lens.

11. A method, comprising:

using a source to generate a first electron beam, electrons in the first electron beam having a polarization with a first orientation, the source comprising:

a base;

a tip fixed to the base and extending from the base, the tip comprising:

a core having a surface comprising a first material; and

a coating on the core, the coating comprising a second material, the second material forming a surface of the tip, and the second material comprising more than 30% by weight of a lanthanide element;

a first electrical terminal electrically connected to the coating;

an extraction electrode having an opening; and

a second electrical terminal electrically connected to the extraction electrode,

wherein the source is an electron beam source, and the first material is different from the second material;

interacting the first electron beam with a sample; and

detecting a first plurality of electrons emerging from the sample as a result of the interaction of the first electron beam with the sample, wherein generating the first electron beam comprises:

setting the tip to a first temperature and applying a first magnetic field to the tip;

then setting the tip to a second temperature lower than the first temperature while maintaining the first magnetic field applied to the tip.

12. The method according to claim 11 , wherein the tip is maintained at the second temperature while detecting the electrons emerging from the sample.

13. The method according to claim 11 , further comprising:

using the source to generate a second electron beam, electrons in the second electron beam having a polarization with a second orientation opposite the first orientation;

interacting the second electron beam with the sample; and

detecting a second plurality of electrons emerging from the sample as a result of the interaction of the second electron beam with the sample.

14. The method according to claim 13 , further comprising comparing an intensity of the first plurality of detected electrons with an intensity of the second plurality of detected electrons.

15. The method according to claim 13 , wherein generating the second electron beam comprises:

setting the tip to a first temperature and applying a magnetic field to the tip; and

then setting the tip to a second temperature while maintaining the magnetic field applied to the tip.

16. The method according to claim 13 , wherein:

generating the second electron beam comprises:

setting tip to the first temperature and applying a second magnetic field to the tip; and

then setting tip to the second temperature while maintaining the second magnetic field applied to the tip.

17. The method according to claim 16 , wherein the second temperature is below 220 K and a magnetic field strength at the tip of the first magnetic field is greater than 0.7 T.

18. The method according to claim 16 , wherein the second temperature is below 250 K and a magnetic field strength at the tip of the first magnetic field is greater than 1.0 T.

19. The source according to claim 1 , wherein the electrical conductivity of the first material is less than 10 5 S/m.

20. The source according to claim 1 , wherein the ratio of the electrical conductivity of the second material to the electrical conductivity of the first material is greater than 10:1.

21. The method according to claim 11 , wherein an electrical conductivity of the first material is less than 10 5 S/m.

22. The method according to claim 11 , wherein a ratio of an electrical conductivity of the second material to an electrical conductivity of the first material is greater than 10:1.