Exchange Splitting in Nickel

Dietz, E.; Gerhardt, U.; Maetz, Christa J.

doi:10.1103/physrevlett.40.892

Cited by 79 publications

(13 citation statements)

References 18 publications

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“…2͑c͒ and 3͑b͒, are small compared with the corresponding LSDA values ͑v F LSDA ͒ by a factor of v F ARPES / v F LSDA ϳ 47-69%, consistent with the observed narrowing of the experimental Ni 3d band width. [5][6][7][8][9] We have estimated the ratio of the Fermi vectors obtained from the ARPES experiment ͑k F ARPES ͒ and the LSDA calculation ͑k F LSDA ͒ as k F ARPES / k F LSDA = 1.0± 0.1 and 0.9± 0.1 for the ⌺ 1 and ⌺ 2 bands, respectively, which is in good agreement with the previous ARPES study. 22 Now the mass enhancement factors due to electron correlation ͑͒ can be evaluated using = ͑k F…”

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confidence: 86%

Energy band and spin-dependent many-body interactions in ferromagnetic Ni(110): A high-resolution angle-resolved photoemission study

et al. 2005

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High-resolution angle-resolved photoelectron spectroscopy of ferromagnetic Ni͑110͒ has been conducted to elucidate energy band and spin-dependent many-body interactions. A kink structure has been clearly observed in the energy band dispersions of the minority spin ⌺ 2↓ and ⌺ 1↓ , while it is absent in the majority spin ⌺ 1↑ band. Analyses of the self-energy indicate that the kink originates from the electron-phonon interaction. Based on a detailed study of the effective mass enhancement, we find that the electron-phonon interaction and electron correlation contribute to the spectral features near the Fermi level in different ways, depending on the identity of the energy band and the spin direction. These results provide insight into the interplay of these many-body interactions on quasiparticles near the Fermi level.

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confidence: 86%

Energy band and spin-dependent many-body interactions in ferromagnetic Ni(110): A high-resolution angle-resolved photoemission study

et al. 2005

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“…Our result for the exchange energy is somewhat higher than the results obtained from spin-resolved photoemission spectroscopy where the splitting between spin-up and spin-down bands at the Fermi energy ranged between 2E ex = 200 meV and 350 meV [18]. The theoretical predictions for 2E ex are typically higher and range from 600 -850 meV [19]. Our value of 2E ex = 400 meV falls in between the above experimental and theoretical values, and is consistent with the values in Ref.…”

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confidence: 73%

Observation of periodicπ-phase shifts in ferromagnet-superconductor multilayers

et al. 2006

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We report complementary studies of the critical temperature and the critical current in ferromagnet (Ni) -superconductor (Nb) multilayers. The observed oscillatory behavior of both quantities upon variation of the thickness of the ferromagnetic layer is found to be in good agreement with theory. The length scale of oscillations is identical for both quantities and is set by the magnetic length corresponding to an exchange field of 200 meV in Ni. The consistency between the behavior of the two quantities provides strong evidence for periodic π phase shifts in these devices.

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“…Equation (5) indicates that the magnitude of JP (2) andF (4) mainly influences the splitting between satellites whereas F (o) determines their mean position. A decrease of F (o) would therefore lower the satellite binding energies in Fig.…”

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confidence: 99%

Effect of Self-Energy Corrections on the Valence-Band Photoemission Spectra of Ni

Liebsch

1979

Phys. Rev. Lett.

365

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It is shown that the experimentally observed band narrowing, the large quasiparticle damping, the small exchange splitting, and the existence of satellites can be reproduced semiquantitatively with use of the low-density approximation to describe correlations between Ni 3d electrons. The exchange splitting of t 2g states (~0.37 eV) is found to be considerably larger than that between e g states (~0.21 eV). A new satellite is predicted about 2 eV below the main "6-eV" satellite.The valence spectra of bulk Ni have received considerable attention since they exhibit several features which cannot be reconciled with the oneelectron band model: (i) the width of the Ni 3d band is about 25% smaller 1 than that predicted theoretically 2 ; (ii) the intrinsic width of spectral features in angle-resolved energy distributions is about 1.2 eV near the bottom of the d band, 3 i.e., much larger than in the case of Cu; (iii) the measured exchange splitting 3 " 5 (0.25-0.35 eV) is approximately half as large as that derived from band theory 2 (0.65 eV); and (iv) a shakeup structure is observed 1 ' 6 at about 6 eV below the Fermi energy.The purpose of the present paper is (a) to predict the existence of yet another satellite at about 2 eV below the main satellite, and (b) to show | ImS" q (o),£) that all four observations described above can be semiquantitatively understood on the basis of correlations among d electrons which determine the spectral distribution of the created hole. The exchange splitting of t 2g states (-0.37 eV) is found to be nearly twice as large as that of e g states (0.21 eV) due to the nonspherical nature of the spin density. The new satellite is predicted to have purely majority spin polarization and to exhibit very weak Fano enhancement. It is shown that this feature is the remnant of the \S term of the atomic d 8 multiplet. The remaining terms combine to a main satellite or merge with the dband states. The spectral function of the hole which is created in the photoemission process is given by the expression A ">>* )= ;rr^ • *Ina -ReS" a (co,1E)J 2 +llmS" a (a;,S)J where €"j" a are the band energies and £ na (co,K), are the diagonal elements of the self-energy matrix. It is assumed that off-diagonal elements can be ignored. The degenerate Hubbard model 7 is used to describe the interactions between d electrons. Since the number of hole states in the Ni d band is small and the interaction between d electrons is short ranged, the low-density approximation is assumed to be adequate. 8 ' 9 In this limit, the self-energy may be written in terms of the t matrix, t = (U" 1 +G (2) )" 1 . G (2) denotes the twoparticle Green's function and U is the intra-atomic Coulomb matrix: a)where p represents the average density and/ the Fermi function. The direct and exchange processes can then be shown to give the following expression for the self-energy 10 : 5 2 a = l j = l (4) ^ = <^m 1 (? 1 )^(? 2 )l^1 2 l^(? 1 )^m 4 (r 2 )),with i^tzg, e g . The n {^ denote the number of holes per minority t^ and^ band and the r a are defin...

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Exchange Splitting in Nickel

Cited by 79 publications

References 18 publications

Energy band and spin-dependent many-body interactions in ferromagnetic Ni(110): A high-resolution angle-resolved photoemission study

Energy band and spin-dependent many-body interactions in ferromagnetic Ni(110): A high-resolution angle-resolved photoemission study

Observation of periodicπ-phase shifts in ferromagnet-superconductor multilayers

Effect of Self-Energy Corrections on the Valence-Band Photoemission Spectra of Ni

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