Spin-polarized electron gun for electron spectroscopies

Ciccacci, Franco; Vescovo, E.; Chiaia, G.; Rossi, Stefano; Tosca, Marco

doi:10.1063/1.1142549

Cited by 52 publications

(24 citation statements)

References 18 publications

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“…33 The spin electron gun was designed in a compact form on a separate chamber equipped with an iodine based Geiger-Müller isochromat photo detector. 34,35 The spin-polarized electrons were emitted from a GaAs photocathode into a spin-rotator 33,36,37 and subsequently to the electron optics. 33,[36][37][38] The direction of electron polarization is in the plane of the sample for all incidence angles, as is the applied field, and spectra were obtained at remanence.…”

Section: Methodsmentioning

confidence: 99%

“…34,35 The spin-polarized electrons were emitted from a GaAs photocathode into a spin-rotator 33,36,37 and subsequently to the electron optics. 33,[36][37][38] The direction of electron polarization is in the plane of the sample for all incidence angles, as is the applied field, and spectra were obtained at remanence. The GaAs photocathode was mounted on a sample transfer arm separated from the spectroscopy chamber by a gate valve so that cleaning of both the Mo͑112͒ substrate and the GaAs photocathode could be accomplished without cross contamination.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Wave-vector-dependent exchange splitting in a local moment system

Waldfried¹,

McAvoy

Welipitiya³

et al. 1998

Phys. Rev. B

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The electronic structure of strained thin films of Gd has been studied with spin-and angle-resolved photoemission and spin-polarized inverse photoemission. The spin-dependent electronic structure is dominated by a very distinct k dependence of the exchange splitting. The surface magnetic structure is observed to be different from that of the bulk, as indicated by the different electronic structure and a much higher surface Curie temperature. The 4% strain within the Gd films results in an enhanced Curie temperature.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Wave-vector-dependent exchange splitting in a local moment system

Waldfried¹,

McAvoy

Welipitiya³

et al. 1998

Phys. Rev. B

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“…In theory the polarization is 50% for GaAs at excitation resonant with the band gap and values approaching this have been measured in experiment. 2,3 Shortly after the invention of the scanning tunneling microscope ͑STM͒, the use of III-V semiconductors and optical orientation was proposed as a possible way of obtaining spin sensitivity in STM. 4,5 The basic idea is to optically excite spin-polarized carriers in a semiconductor STM tip and thereby create a spin-dependent occupation of the energy levels.…”

Section: Introductionmentioning

confidence: 99%

Theory of spin-polarized transport in photoexcited semiconductor/ferromagnet tunnel junctions

1998

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We present a theory for spin-polarized transport in tunnel junctions consisting of a ferromagnet and a semiconductor, in which spin-polarized carriers are created by optical orientation. The model includes, for both spin orientations, the current due to tunneling between the ferromagnet and the semiconductor surface as well as the photoinduced and the thermionic emission currents through the semiconductor subsurface region. Tunneling is described in terms of a spin-dependent tunnel conductance, taking account of the magnetic structure of the ferromagnet. We consider spin depolarization of photoexcited electrons in the semiconductor bulk material and in surface states that have a spin-dependent occupation. The total tunnel current is evaluated as well as current modulations due to modulated spin polarization of photoelectrons ͑CPM signal͒ or modulated optical intensity. The calculations show that the CPM signal is proportional to the tunnel conductance polarization and is relatively insensitive to spin depolarization of photoelectrons during their transport to the surface. A severe signal reduction can, however, result from spin relaxation in semiconductor surface states. In addition, it is demonstrated that a crucial role is played by the operating regime of the junction, i.e., photoamperic or photovoltaic, where the selection is determined mainly by the choice of applied bias voltage. We find that the photovoltaic mode is favored, as it yields the highest contribution from spin-polarized tunneling, combined with the smallest sensitivity for unwanted light intensity modulations. ͓S0163-1829͑98͒03207-X͔

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“…13 The Fe͑001͒ sample is obtained by growing a 300-nm-thick Fe film onto a MgO͑001͒ substrate in UHV conditions. After annealing at 850 K, a clean and ordered Fe͑001͒ surface is obtained as evidenced by x-ray photoemission spectroscopy ͑XPS͒ and low-energy electron diffraction ͑LEED͒ analysis.…”

Section: Experimental and Theoretical Detailsmentioning

confidence: 99%