Experimental determination of the phase differences of continuum wavefunctions describing the photoionisation process of xenon atoms. I. Measurements of the spin polarisations of photoelectrons and their comparison with theoretical results

Heinzmann, Ulrich

doi:10.1088/0022-3700/13/22/010

Cited by 118 publications

(61 citation statements)

References 39 publications

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“…The size of P is related to the phase shift of the complex matrix elements describing the transitions under consideration [17][18][19]. One can, therefore, access the phase information by measuring the spin polarization of the photoelectrons.…”

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confidence: 99%

Spin polarization in photoemission from the cuprate superconductor Bi2Sr2CaCu2O8+δ

et al. 2017

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Photoelectrons produced from the excitation of spin-degenerate states in solids can have a sizable spin polarization, which is related to the phase of interfering channels in the photoemission matrix elements. Such spin polarization can be measured by spin-resolved photoemission spectroscopy to gain information about the transitions and the Wigner time delay of the process. Incorporating strongly correlated electron systems into this paradigm could yield a novel means of extracting phase information crucial to understanding the mechanism of their emergent behavior. In this work, we present, as a case study, experimental measurements of the cuprate superconductor Bi 2 Sr 2 CaCu 2 O 8+δ by spin-resolved photoemission while maintaining full angular and energy resolution. A spin polarization of at least 10% is observed, which is related to the phase of the photoelectron wave function. DOI: 10.1103/PhysRevB.95.245125 The electronic properties of crystals are best understood when information on their band structure can be obtained. Angle-resolved photoemission spectroscopy (ARPES) provides a direct means of reconstructing the band structure by measuring the energies and momenta of electrons photoexcited from a solid [1]. Spin-and angle-resolved photoemission spectroscopy (SARPES), in addition, measures the spin polarization P of the photoelectron beam as a function of emission angle and kinetic energy. This can show a net polarization if the initial state is polarized as, for example, in ferromagnets [2,3] or spin-momentum-locked systems, such as Rashba-like materials [4][5][6] and topological insulators [7][8][9][10], but also as a result of the photoemission process as a whole [11]. If the incident light is circularly polarized, i.e., it carries angular momentum, the spin polarization of the photoelectron beam from solid-state targets can, in several different circumstances, be interpreted as a result of the selection rules for the considered transitions along the lines of the atomic Fano effect [12][13][14][15][16].Also, when the incident light is linearly polarized or unpolarized, i.e., it does not transfer a net angular momentum, the photoelectron beam can still present a sizable P. The origin of this effect lies in the symmetry reduction of angledependent photoemission and in the interference of different photoemission channels. The size of P is related to the phase shift of the complex matrix elements describing the transitions under consideration [17][18][19]. One can, therefore, access the phase information by measuring the spin polarization of the photoelectrons. In particular, a novel application of SARPES is the estimate of the Eisenbud-Wigner-Smith (EWS) time delay [20] τ EWS of photoemission, defined as the derivative of the phase shift with respect to the photoelectron kinetic energy, obtained from the measured P, as shown in Ref. [19] for the model system Cu(111). By expressing the spin polarization as a function of the radial parts and phase shifts of the matrix elements, along the lines of the ato...

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Spin polarization in photoemission from the cuprate superconductor Bi2Sr2CaCu2O8+δ

et al. 2017

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“…The error bars, indicating the statistical uncertainty of the averaging, are smaller than the point size. The full line represents the result of a least-squares fit to (8). From the fit, the values for/max and I~in are determined, which then give the degree of linear polarization according to [38]:…”

Section: Vuv Polarizationmentioning

confidence: 99%

“…In atoms, the higher spherical symmetry leads to the selection rule for the angular momentum of the photoelectron and the total angular momentum of the system Ae=±l and AJ=0, ±1, respectively, which restricts the number of dipole matrix elements to be considered in the analysis of an experiment on closed shell systems to three. In this case, five independent observables prove to be sufficient for a quantum mechanically complete description of the photoionization experiment [8]. In molecules, this is generally not possible.…”

Section: Introductionmentioning

confidence: 99%

Angle- and spin-resolved photoelectron spectroscopy in rotationally resolved photoionization of HI

Mank

Drescher

Brockhinke

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The method of angle-and spin-resolved photoelectron spectroscopy has been used in combination with a laser based source of vacuum ultraviolet (VUV) radiation to study the photoionization dynamics of the HI molecule. The narrow bandwidth (3 v < 1 cm-1) of the ionizing VUV radiation (v = 83 200 cm-1 _ 89 300 cm 1) enables the resolution of the molecular rotation for single-photon excitation to spin-orbit autoionization resonances. The experimental results for the dynamical parameters a, A, fl, %, and ~ are compared to the results of a recent ab-initio calculation (M. Biichner, G. Raseev, and N.A. Cherepkov, J. Chem. Phys. 96, 2696 (1992)) and used to analyze the photoionization process in terms of partial contributions of different values of I and 2 to the outgoing electron waves.

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“…Right handed CPR has negative helicity (σ-radiation) and the photon spin (-ħ) is antiparallel to the propagation direction of light. magnets of storage rings slightly above and below the ring planes [5], while the radiation in the ring plane is linearly polarized (π-radiation). Though x-radiation occurs thus very generally, experiments with circularly polarized synchrotron radiation were until recently rather the exception than the rule, because most of the monochromation do not transmit the high degree of circular polarization to the samples studied.…”

Section: Sources Of Circularly Polarized Radiationmentioning

confidence: 99%

“…Though x-radiation occurs thus very generally, experiments with circularly polarized synchrotron radiation were until recently rather the exception than the rule, because most of the monochromation do not transmit the high degree of circular polarization to the samples studied. In the XUV range few monochromation for circularly polarized synchrotron radiation work at normal incidence [5,6] or use monochro mation for linearly polarized light in combination with phase shifting elements. Both techniques yield almost completely polarized radiation but only for photon energies below about 35 eV.…”

Section: Sources Of Circularly Polarized Radiationmentioning

confidence: 99%

X-Ray Absorption and Experiments with Circularly Polarized Radiation

Schmiedeskamp

1994

Acta Phys. Pol. A

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Absorption of circularly polarized radiation (x-radiation) recently gained interest mainly due to its helicity-dependence for magnetic materials (circular magnetic dichroism). The physics behind this absorption process is optical orientation and is closely related to the physics behind other types of experiment with circularly polarized radiation in which fundamental electronic properties of matter are studied. The consideration of X-ray absorption plays also a role in the development of new beam lines for x-radiation. An important part in a beamline for x-radiation in the soft X-ray range can be multilayer optics. The role of absorption in the design of these optics is discussed as well as different types of experiment with circularly polarized radiation: the physical mechanism of optical orientation is applied to gain insight into both magnetic and fundamental electronic properties of matter.

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Experimental determination of the phase differences of continuum wavefunctions describing the photoionisation process of xenon atoms. I. Measurements of the spin polarisations of photoelectrons and their comparison with theoretical results

Cited by 118 publications

References 39 publications

Spin polarization in photoemission from the cuprate superconductor Bi2Sr2CaCu2O8+δ

Spin polarization in photoemission from the cuprate superconductor Bi2Sr2CaCu2O8+δ

Angle- and spin-resolved photoelectron spectroscopy in rotationally resolved photoionization of HI

X-Ray Absorption and Experiments with Circularly Polarized Radiation

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