Temperature Dependence of the Exchange Splitting in Ni Studied by Spin-Polarized Photoemission

Hopster, H.; Raue, R.; Güntherodt, G.; Kisker, E.; Clauberg, R.; Campagna, M.

doi:10.1103/physrevlett.51.829

Cited by 123 publications

(27 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8 The result of this procedure is shown in figure 4(b), for polarization vectors as indicated in figure 4(d). It can be noted that peak I 1 (k x ) is assigned a polarization vector P 1 ≈ (0, 1, 0) and therefore shows up only in the I ↑ y (k x ) spectrum, while I 2 (k x ) points almost in the opposite direction and shows up predominantly in the I ↓ y (k x ) spectrum.…”

Section: Analysis Of Spin-polarized Arpes Datamentioning

confidence: 99%

“…The extra information contained in such spin-resolved spectra can provide very detailed information on exchange splittings and the magnetization state in magnetic systems [8], or in the case of surface states with strong spin-orbit interaction, on the splitting of Kramers pairs 5 [12], the degree of spin polarization of individual bands [13], and the detailed spin texture at the Fermi surface [14,15]. Moreover, the spin polarization provides an extra tag in such systems that permits to observe splittings smaller than the intrinsic width of the individual peaks that could not be resolved with regular ARPES [16].…”

Section: Introductionmentioning

confidence: 99%

“…The spin of the electron represents an extra set of observables, provided that the spin polarization of the photoelectrons can be measured as in spin-resolved ARPES (SARPES) [8]. The quantum mechanical operator governing the photoemission process does not couple directly to the electron spin, and therefore the photoelectron carries in principle, and in the absence of magnetic fields along its pathway, the spin from the initial state all the way to the detector 4 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Measuring spin polarization vectors in angle-resolved photoemission spectroscopy

Meier¹,

Dil²,

Osterwalder³

2009

New J. Phys.

View full text Add to dashboard Cite

Section: Analysis Of Spin-polarized Arpes Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Measuring spin polarization vectors in angle-resolved photoemission spectroscopy

Meier¹,

Dil²,

Osterwalder³

2009

New J. Phys.

View full text Add to dashboard Cite

“…Insight into this question has also been gained from photoemission and inverse photoemission experiments [6][7][8][9][10][11][12], and again conflicting views were obtained with respect to the temperature dependence of DE ex . Recent experiments found that spin-split bands merged with temperature at some k locations while their splitting remained temperature independent at others [10].…”

mentioning

confidence: 99%

k-Space Mapping of Majority and Minority Bands on the Fermi Surface of Nickel below and above the Curie Temperature

et al. 1996

View full text Add to dashboard Cite

A section through the three-dimensional Fermi surface of Ni has been mapped perpendicular to the [110] direction using angle-scanned photoemission. Regions of minority and majority spin bands, well separated in k space, can clearly be identified through comparison with a band structure calculation. The behavior of the different bands is observed for temperatures below and above the Curie temperature T C . We find bands which move and bands which stay in place for going from T , T C to T . T C .Despite a large amount of experimental data on the electronic and magnetic structure of nickel, conflicting conclusions persist about the behavior of the exchange splitting DE ex as a function of temperature [1][2][3][4][5]: While some experiments point to a largely temperatureindependent exchange splitting in going across the Curie temperature (T C 631 K) others give evidence for changes of the Fermi surface (FS) in traversing T C . Insight into this question has also been gained from photoemission and inverse photoemission experiments [6][7][8][9][10][11][12], and again conflicting views were obtained with respect to the temperature dependence of DE ex . Recent experiments found that spin-split bands merged with temperature at some k locations while their splitting remained temperature independent at others [10]. Inverse photoemission studies [12] reported on collapsing spinsplit bands upon approaching T C even for the magnetic Z 2 band, and the experimentally determined exchange splitting followed the rescaled bulk magnetization curve.Considering these results showing both temperatureindependent or collapsing exchange splittings, and thus indicating at the same time the persistence of local moments and a Stoner-type behavior, it is important to obtain a more systematic view of the temperature behavior of DE ex in k space, and, in particular, of the magnetic bands crossing the Fermi level ͑E F ͒. We therefore present a highresolution temperature-dependent mapping of a complete section through the FS of Ni, as viewed through the (110) surface, in which several magnetic bands are observed at the same time. It is important to note that the present experiment resolves majority and minority bands in k space.Recently, Santoni et al.[13] used a two-dimensional display-type analyzer to map the FS of layered graphite directly by measuring the total photoelectron intensity within a narrow energy window at E F . High intensities are recorded at locations of the wave vector component parallel to the surface ͑k k ͒ where direct transitions disperse through this window, namely, through the FS. In the present work we use sequential angle-scanning data acquisition [14], providing a high energy resolution and access to a wide range in k space. Recently we demonstrated the efficiency and accuracy of this method by measuring the two-dimensional FS of a Bi cuprate [15] and cuts through the three-dimensional FS of Cu [16]. The obvious advantage of this procedure is that it provides a very accurate intensity mapping with a selectable uniform ...

show abstract

“…Itinerant ferromagnetism in late transition metals at finite temperatures has been for a long time a subject of scientific debate [1]. Neutron scattering experiments [2] and also photoemission measurements on Ni [3,4] at high temperatures have in particular stimulated much discussion on the validity of the simple Stoner-Wohlfarth meanfield theory [5] which predicts the collapse of exchange splitting above the Curie temperature ͑T C ͒ and the disappearance of local moments. Observations of different k dependent exchange splitting behavior with temperature gave rise not only to fluctuating band theory [6] which assumes the persistence of a certain degree of short-range magnetic order above T C , but also to the two-pole ansatz plus effective medium approach for the Hubbard model [7] which predicts the retention of local moments above T C together with a collapse of the exchange splitting.…”

mentioning

confidence: 99%

Local Electronic and Magnetic Structure of Ni below and aboveTC: A Spin-Resolved Circularly Polarized Resonant Photoemission Study

et al. 1997

View full text Add to dashboard Cite

We report the measurement of the local Ni 3d spin polarization, not only below but also above the Curie temperature ͑T C ͒, using the newly developed spin-resolved circularly polarized 2p ͑L 3 ͒ resonant photoemission technique. The experiment identifies the presence of 3d 8 singlets at high energies and 3d 8 triplets at low energies extending all the way to the Fermi energy, both below and above T C , showing that it is the orbital degeneracy of the 3d band and the Hund's rule splitting which is of utmost importance to understand Ni and other 3d ferromagnets. [S0031-9007(97) PACS numbers: 75.20.En, 75.25. + z, 79.60.Bm Itinerant ferromagnetism in late transition metals at finite temperatures has been for a long time a subject of scientific debate [1]. Neutron scattering experiments [2] and also photoemission measurements on Ni [3,4] at high temperatures have in particular stimulated much discussion on the validity of the simple Stoner-Wohlfarth meanfield theory [5] which predicts the collapse of exchange splitting above the Curie temperature ͑T C ͒ and the disappearance of local moments. Observations of different k dependent exchange splitting behavior with temperature gave rise not only to fluctuating band theory [6] which assumes the persistence of a certain degree of short-range magnetic order above T C , but also to the two-pole ansatz plus effective medium approach for the Hubbard model [7] which predicts the retention of local moments above T C together with a collapse of the exchange splitting. However, despite a large body of experimental data, a complete description of the finite temperature magnetism remains controversial, with some recent results on Ni supporting a Stoner-like behavior [8], fluctuating band theory [9], or suggesting even more complex behavior [10]. And as far as the electronic structure is concerned, most of this discussion can be reduced to the question as to whether or not the atomic Hund's rule correlations have survived the strong band formation. Such local exchange interactions, together with the suppression of charge fluctuations due to Coulomb interactions, may not account only for the failure of mean-field theories to calculate T C properly, but, more important, may also give a plausible explanation for the retention of local moments and short-range magnetic order above T C in late transition metals [11].To provide a better insight in these phenomena, we have investigated the local electronic structure of Ni and its temperature dependence, with special emphasis on the spin polarization of the atomiclike 3d orbitals. For this we have used the spin-resolved circularly polarized 2p ͑L 3 ͒ resonant photoemission technique, a newly developed spectroscopic tool with the unique property that it is capable of measuring the local 3d spin polarization independent of the orientation of the local moment, which is a necessary condition to study local moments above T C . We have been able to observe a strong spin polarization in the valence band of Ni, not only below but also above T ...

show abstract

Temperature Dependence of the Exchange Splitting in Ni Studied by Spin-Polarized Photoemission

Cited by 123 publications

References 16 publications

Measuring spin polarization vectors in angle-resolved photoemission spectroscopy

Measuring spin polarization vectors in angle-resolved photoemission spectroscopy

k-Space Mapping of Majority and Minority Bands on the Fermi Surface of Nickel below and above the Curie Temperature

Local Electronic and Magnetic Structure of Ni below and aboveTC: A Spin-Resolved Circularly Polarized Resonant Photoemission Study

Contact Info

Product

Resources

About