| 1. |
- Brookes, N. B., et al.
(författare)
-
Detection of Zhang-Rice singlets using spin-polarized photoemission
- 2001
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 8723:23
-
Tidskriftsartikel (refereegranskat)abstract
- From a spin-resolved photoemission study on the Bi2Sr2CaCu2O8+delta superconductor, we show experimentally that the first ionization state is of nearly pure singlet character. This is true both above and below the superconducting transition and in the presence of doping and band formation. This provides direct support for the existence and stability of Zhang-Rice singlets in high-temperature superconductors, justifying the ansatz of single-band models. Moreover, we establish this technique as an important probe for a wide range of cuprates and strongly correlated materials.
|
|
| 2. |
- Konishi, T, et al.
(författare)
-
Electronic structure of the strongly hybridized ferromagnet CeFe2
- 2000
-
Ingår i: PHYSICAL REVIEW B. - : AMERICAN PHYSICAL SOC. - 0163-1829. ; 62:21, s. 14304-14312
-
Tidskriftsartikel (refereegranskat)abstract
- We report on results from high-energy spectroscopic measurements on CeFe2, a system of particular interest due to its anomalous ferromagnetism with an unusually low Curie temperature and small magnetization compared to the other rare-earth iron Laves phas
|
|
| 3. |
- Konishi, T, et al.
(författare)
-
Photoemission and inverse-photoemission study of ferromagnetic valence fluctuating system CeFe2
- 1998
-
Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 88, s. 303-307
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Various electron-spectroscopic results including core-level X-ray photoemission, X-ray absorption, Ce 3d-4f and 4d-4f resonant photoemission, and inverse-photoemission spectroscopy on the valence fluctuating ferromagnet CeFe2 are presented and analyzed wi
|
|
| 4. |
- Ghiringhelli, G., et al.
(författare)
-
3d spin-orbit photoemission spectrum of nonferromagnetic materials : The test cases of CoO and Cu
- 2002
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:7
-
Tidskriftsartikel (refereegranskat)abstract
- The x-ray photoemission spectrum of the valence states of 3d transition-metal systems is spin polarized when using circularly polarized photons. The integral of the spin-orbit spectrum is proportional to the expectation value of the angular part of the 3d spin-orbit operator in the initial state. We show that this quantity can be used to get an estimate of the atomic orbital moment. While the measurement is sensitive to the magnetization axis, it does not require a net macroscopic magnetization nor the presence of a long-range magnetic order, and is therefore suitable for any transition-metal systems being antiferromagnetic or paramagnetic or magnetically disordered. In the case of full 3d shell the integral of the spin-orbit spectrum is zero, but the spectral shape can give a direct estimate of the 3d spin-orbit energy splitting DeltaE(SO). We have used Cu and CoO to experimentally test this technique. As expected Cu provides a vanishing result for , whereas for Co2+ in CoO we find =1.36h at 0 K. On the other hand we find DeltaE(SO)similar or equal to280 meV for Cu.
|
|
| 5. |
- Ghiringhelli, G., et al.
(författare)
-
Probing the singlet character of the two-hole states in cuprate superconductors
- 2002
-
Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 312, s. 34-35
-
Tidskriftsartikel (refereegranskat)abstract
- Using spin-resolved resonant photoemission we have probed the singlet vs. triplet character of the two-hole state in the layered cuprates Bi2Sr2CaCu2O8+delta La2-xSrxCuO4 and Sr2CuO2Cl2. The combination of the photon circular polarization with the photoelectron spin detection gives access to the character of the photoemission final states, which correspond to the two-hole configurations localized at a (CuO4) site. In particular, the lowest energy state is found to have a very high singlet character in all the measured compounds. This can be considered as a strong indication of the existence and stability of the so-called Zhang-Rice singlets in the layered cuprates.
|
|
| 6. |
|
|
| 7. |
- Mizokawa, T., et al.
(författare)
-
Spin-orbit coupling in the Mott insulator Ca2RuO4
- 2001
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 8707:7
-
Tidskriftsartikel (refereegranskat)abstract
- O 1s x-ray absorption study of the Mott insulator Ca2RuO4 shows that the orbital population of the 4d t(2g) band dramatically changes with temperature. In addition, spin-resolved circularly polarized photoemission study of Ca2RuO4 shows that a substantial orbital angular momentum is induced in the Ru 4d t(2g) band. Based on the experimental results and model Hartree-Fock calculations, we argue that the cooperation between the strong spin-orbit coupling in the Ru 4d t(2g) band and the small distortion of the RuO6 octahedra causes the interesting changeover of the spin and orbital anisotropy as a function of temperature.
|
|
