Magnetic dichroism and electron spin polarization in photoemission: analytical results

Ab initio and model calculations demonstrate that the spin motion of electrons transmitted through ferromagnetic films can be analyzed in detail by means of angle-and spin-resolved corelevel photoelectron spectroscopy. The spin motion appears as precession of the photoelectron spin polarization around and as relaxation towards the magnetization direction. In a systematic study for ultrathin Fe films on Pd(001) we elucidate its dependence on the Fe film thickness and on the Fe electronic structure. In addition to elastic and inelastic scattering, the effect of band gaps on the spin motion is addressed in particular.

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“…The dependence of P tr on ϕ ph (left panel) follows perfectly that derived analytically in Ref. [11].…”

Section: ↑(↓)supporting

confidence: 81%

“…Hence, the commonly used external GaAs source for spin-polarized electrons is, so to speak, replaced by an internal one, with the advantage of easy orientation of P in . Choosing other light polarizations and incidence directions one can produce P in with a component along the surface normal [11].…”

mentioning

confidence: 99%

Spin motion of photoelectrons

et al. 2003

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“…There is an unexplained detail in the experimental data: the finite spin polarization at normal emission of S 1 . SOC can induce a finite spin polarization of the photoelectrons in highly symmetric setups [15,30,31]. Our experiments show this for the not intrinsically spin-polarized and almost pure d z 2 surface state; that the effect originates from the ARPES measurements is supported by its photon-energy dependence.…”

supporting

confidence: 52%

Spin-orbit influence ondz2-type surface state at Ta(110)

et al. 2015

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The influence of spin-orbit interaction on an occupied surface state at Ta (110) is investigated with spin-and angle-resolved photoemission and electronic structure calculations. The surface state appears in a symmetry gap at a binding energy of 0.45 eV at and exhibits a free-electron-like E(k ) dispersion with an effective mass m * /m e of about − Spin-orbit coupling (SOC) is known to affect the electronic structure of solids with heavy elements, in particular, by lifting the spin degeneracy of surface states [1][2][3][4]. The resulting Rashba-type spin dependence is locked with the direction of the electron momentum. Tantalum is a heavy element with a pronounced surface state at the (110) surface [5][6][7]. This state appears just below the Fermi level around the center of the surface Brillouin zone within a gap for bulk bands of even symmetry. However, no hybridization with odd-symmetry bulk states was observed and thus no influence of spin-orbit coupling was found in the results [5]. It was concluded that "the spin-orbit interaction does not strongly impact this state" [6]. A predominant d z 2 symmetry character of 93% was calculated for this state around , "which accounts for the lack of dispersion" [7].In contrast, the direct neighbor in the periodic table, tungsten, with the same crystal structure (body-centeredcubic) and a very similar band structure, exhibits a wealth of spin-orbit-induced effects in the surface electronic structure [8][9][10][11][12][13][14][15]. Therefore, spin-orbit effects are expected for Ta as well. Recently, spin-polarized unoccupied surface bands were identified on Ta(110), whose spin dependence originates from SOC [16]. There is apparently substantial impact of SOC in the unoccupied states, which strongly suggests that SOC should influence the occupied states as well. The latter is at variance with earlier claims. To resolve this contradiction, we revisit the occupied d z 2 -type surface state at Ta(110), now using angle-resolved photoelectron spectroscopy (ARPES) with spin detection. The study is of further importance because W(110) has no equivalent to the d z 2 -like surface state of Ta (110) Prototypical d z 2 -type surface states are known from the (0001) surfaces of hexagonal-closed-packed lanthanide surfaces. Indications for a spin-orbit-induced Rashba-type splitting, enhanced by an oxygen-induced modification of the surface potential, have been observed by spin-integrated ARPES for Lu (Z = 71) but not for Y (Z = 39) [18]. In the cases of ferromagnetic Gd (Z = 64) and Tb (Z = 65), the magnetic exchange interaction dominates the spin-orbit interaction [18][19][20]. Nevertheless, a small energy shift of the surface band, asymmetric in k , was observed upon switching the magnetization direction. The shift, observed by spin-integrated ARPES, was attributed to the Rashba splitting. This approach is restricted to ferromagnetic samples. With these results in mind, Ta (Z = 73) is a promising candidate for studying spin-orbit effects on a localized d z 2 -type surface state even...

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“…In the following, we will discuss our results in the framework of a theoretical study [46]. In this work, dipole transition matrix element effects for off-normally incident linear polarized light on non-magnetic materials with C 2v symmetry are considered.…”

Section: Spin-dependent Intensities Of S 1 For Normal Electron Emissionmentioning

confidence: 99%