Evidence for Short-Range Magnetic Order in Ni above<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>

Maetz, Christa J.; Gerhardt, U.; Dietz, E.; Ziegler, A.; Jelitto, R. J.

doi:10.1103/physrevlett.48.1686

Cited by 73 publications

(11 citation statements)

References 20 publications

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“…The low-velocity states, which carry the magnetization, remain split. At higher velocity there is central-peak structure, as reported earlier 8,9 for spin-unresolved spectra on the (111) face. (We remark that this central peak is the sum of two spin-polarized peaks.…”

Section: Energy Belowsupporting

confidence: 52%

Local-Band-Theory Analysis of Spin-Polarized, Angle-Resolved Photoemission Spectroscopy

Korenman

Prange

1984

Phys. Rev. Lett.

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We present the local-band theory of the temperature dependence of up-and down-spin Green's functions in itinerant-electron ferromagnets. The results, calculated for a temperature-independent, local, exchange field strength, and under the assumption of the existence of short-range magnetic order, agree with recent measurements of angle-, energy-, and spin-resolved photoemission in nickel. States which contribute to the magnetization, not seen in the measurements, remain split in energy even at T c . Split states at T c are also expected in iron.PACS numbers: 75.10.Lp, 79.60.CnAngle-, energy-, and spin-resolved photoemission (ARPES) ideally is interpreted as the annihilation of a bulk electron of definite energy, momentum, and spin (and the creation of a high-energy electron which escapes and is measured). It measures the spectral density of the single-hole Green's function. The spin of this hole acts as a probe of the magnetic condition of the solid through which it propagates.The beautiful experiments of Hopster et al l using ARPES to study the magnetic properties of nickel have thus generated much interest, especially as it was claimed that no existing picture of hightemperature itenerant-electron magnetism is consistent with the results. It is our purpose here to show that the "local-band picture" is so consistent. It remains to be seen whether the "alloy analogy" picture is also consistent, as that theory has not been worked out for realistic bands. 2 The local-band picture 3,4 stresses the existence of short-range magnetic order which remains on a scale of about 20 A ( = 27r/a) above T c . This allows spin-split energy bands to be quite well defined locally. The alloy analogy 5,6 idea is to neglect short-range order and assume atomically random mean spins, enabling an exploitation of the coherent potential approximation.The question is to discuss the propagation of a hole starting with definite spin through two such different magnetic media. The results depend on the parameters of the hole state. There are two limiting cases. Namely, suppose the hole moves fast enough that the exchange field it sees changes direction in a time short compared to that which it takes its spin to align itself to the exchange field. The spin of such fast holes in effect sees the average magnetization, i.e., there is a motional narrowing. The spectral density will peak at different energies for spin up and spin down with the energy difference between peaks proportional to the magnetization. The spin of slow holes, on the other hand, follows the local magnetization and remains in approximate alignment or antialignment with it. There will be two peaks in the spectral density of each spin whose weights are coupled to the bulk magnetization, but which are split by the local magnetization.Thus the critical parameter is Ha v/A, where A is the spin splitting of the hole and v its velocity.(The minimum value of v is Ha/m, with m the hole mass.) For nickel, the probing holes in the actual experiment have small mass and relatively small A le...

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Section: Energy Belowsupporting

confidence: 52%

Local-Band-Theory Analysis of Spin-Polarized, Angle-Resolved Photoemission Spectroscopy

Korenman

Prange

1984

Phys. Rev. Lett.

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“…Our results are also in agreement with ARPES measurements. 31,32 The EMTO-DMFT magnetic moment of 0.42 B , see Table I, represents a reduction of 30% from the LSDA value. This reduction is comparable with 25% evidenced from experimental magnetic moments.…”

Section: B Nimentioning

confidence: 99%

Ab initioelectronic structure calculations of correlated systems: An EMTO-DMFT approach

et al. 2003

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We propose a self-consistent method for electronic structure calculations of correlated systems, which combines the local spin-density approximation ͑LSDA͒ and the dynamical mean field theory ͑DMFT͒. The LSDA part is based on the exact muffin-tin orbital approach, meanwhile the DMFT uses a perturbation scheme that includes the T matrix with fluctuation exchange approximation. The current LSDAϩDMFT implementation fulfills both self-energy and charge self-consistency requirements. We present results on the electronic structure calculations for bulk 3d transition metals ͑Cr, Fe, and Ni͒ and for Fe/Cr magnetic multilayers. The latter demonstrates the importance of the correlation effects for the properties of magnetic heterostructures.

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“…The three-peak analysis forming the basis for the ''evidence for short-range magnetic order in nickel above T C '' with a temperature-independent ⌬E ex published in Ref. 21 has been shown to rely on a false interpretation of an LBT calculation. 14 In Ref.…”

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confidence: 99%

Temperature-dependent electronic structure of nickel metal

et al. 1998

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An extended set of temperature-dependent ARUPS data from Ni͑111͒ is presented. The ferromagnetic and the paramagnetic state as well as the phase transition are examined in great detail. Rather new and unconventional modes of data acquisition in ARUPS are applied with high angular and energy resolution, exhibiting great power near the Fermi energy E F . Even up to 5k B T above E F energy bands are readily observed. The understanding of these ARUPS data is strongly enhanced by spin-polarized band structure calculations. Exchange-split bands of both, sp-and d-character, are resolved in angular scans and in photoemission Fermisurface maps. From two-dimensional data sets in energy and angle the dispersion and the exchange splitting are obtained with high precision. All the observed sp-and d-bands clearly exhibit a Stoner-like collapsing-band behavior. The exchange splitting ⌬E ex vanishes above T C in all cases, and ⌬E ex closely follows the temperature dependence of the macroscopic magnetization. The apparent deviations from the Stoner-like band behavior stated in P. Aebi et al., Phys. Rev. Lett. 76, 1150 ͑1996͒ are explained. Furthermore we detect anomalously high intensity from a minority d-band close to an sp-band. This strongly suggests that sp-d-fluctuations at the Fermi level are a driving force for the magnetic phase transition of nickel.

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Evidence for Short-Range Magnetic Order in Ni aboveTc

Cited by 73 publications

References 20 publications

Local-Band-Theory Analysis of Spin-Polarized, Angle-Resolved Photoemission Spectroscopy

Local-Band-Theory Analysis of Spin-Polarized, Angle-Resolved Photoemission Spectroscopy

Ab initioelectronic structure calculations of correlated systems: An EMTO-DMFT approach

Temperature-dependent electronic structure of nickel metal

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