Abstract
A theory is given for field emission from ferromagnetic solids in which the two spin subbands of the conduction band are split by exchange forces. Using a simple plane wave model for the conduction band states it is shown that the familiar WKB approximation for the tunneling probability has to be improved by momentum dependent factors to account for the spin polarization of the emission current observed in a recent experiment which is 8% in the case of Gd. The calculations are extended to describe emission from Bloch states. Applications of the theory to various ferromagnetic systems are discussed, the use of ferromagnetic Eu1−xGdxS as a source for highly polarized beams is suggested.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Work supported by the National Science Foundation.
On leave from Technische Hochschule München, Germany.
The author wishes to acknowledge valuable discussions with Dipl. Phys. N.Müller, Drs. H.Siegmann and W.Zinn and Professor G.H.Wannier.
Rights and permissions
About this article
Cite this article
Obermair, G. Theory of polarized electron beam production by field emission from ferromagnets. Z. Physik 217, 91–112 (1968). https://doi.org/10.1007/BF01390642
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF01390642