Abstract
High temperature superconductivity is achieved by hole doping of parent compounds, which undergo a phase transition from the antiferromagnetic, insulating state to the metallic and superconducting state. This development can only be studied continuously on few members of the cuprate family: Bi{sub 2}Sr{sub 2}Ca{sub 1-x}Y{sub x}Cu{sub 2}O{sub 8+{delta}} single crystals, where the hole concentration in the two CuO{sub 2}-planes per unit cell (n=2) is controlled by the substitution of Ca by Y, and Bi{sub 2}Sr{sub 2}Ca{sub 1-} {sub x}La{sub x}CuO{sub 6+{delta}} single crystals, where this concentration in the one CuO{sub 2}-plane per unit cell (n=1) is controlled by the substitution of Sr by La enable this study of the doping dependence over a wide range of hole concentrations with ARPES. Investigations of antiferromagnetic parent compounds have so far mostly been reported for oxychlorides, like e.g. Sr{sub 2}CuO{sub 2}Cl{sub 2} and discussed within the t-t'-t'''-J model. Since the character of the CuO derived states near the Fermi level is decisive for the electronic structure, it will be discussed, whether this or other models like the generalized tight binding method (GTBM) give an appropriate description. A detailed treatment by this method with a five band Hubbard Hamiltonian, i.e. involving planar and off
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Janowitz, C
[1]
- Humboldt Universitaet zu Berlin, Institut fuer Physik, Berlin (Germany)
Citation Formats
Janowitz, C.
Exploring the phase diagram of the Bi-cuprates by photoemission[Full text article has been submitted to the ''Journal of Alloys and Compounds'' (Elsevier)].
Poland: N. p.,
2004.
Web.
Janowitz, C.
Exploring the phase diagram of the Bi-cuprates by photoemission[Full text article has been submitted to the ''Journal of Alloys and Compounds'' (Elsevier)].
Poland.
Janowitz, C.
2004.
"Exploring the phase diagram of the Bi-cuprates by photoemission[Full text article has been submitted to the ''Journal of Alloys and Compounds'' (Elsevier)]."
Poland.
@misc{etde_20616791,
title = {Exploring the phase diagram of the Bi-cuprates by photoemission[Full text article has been submitted to the ''Journal of Alloys and Compounds'' (Elsevier)]}
author = {Janowitz, C}
abstractNote = {High temperature superconductivity is achieved by hole doping of parent compounds, which undergo a phase transition from the antiferromagnetic, insulating state to the metallic and superconducting state. This development can only be studied continuously on few members of the cuprate family: Bi{sub 2}Sr{sub 2}Ca{sub 1-x}Y{sub x}Cu{sub 2}O{sub 8+{delta}} single crystals, where the hole concentration in the two CuO{sub 2}-planes per unit cell (n=2) is controlled by the substitution of Ca by Y, and Bi{sub 2}Sr{sub 2}Ca{sub 1-} {sub x}La{sub x}CuO{sub 6+{delta}} single crystals, where this concentration in the one CuO{sub 2}-plane per unit cell (n=1) is controlled by the substitution of Sr by La enable this study of the doping dependence over a wide range of hole concentrations with ARPES. Investigations of antiferromagnetic parent compounds have so far mostly been reported for oxychlorides, like e.g. Sr{sub 2}CuO{sub 2}Cl{sub 2} and discussed within the t-t'-t'''-J model. Since the character of the CuO derived states near the Fermi level is decisive for the electronic structure, it will be discussed, whether this or other models like the generalized tight binding method (GTBM) give an appropriate description. A detailed treatment by this method with a five band Hubbard Hamiltonian, i.e. involving planar and off planar states of the CuO-planes shows, that the first removal state is composed not only from the Zhang-Rice singlet state but also from states with spin triplet character. In the second part of the talk the electronic structure for hole concentrations in the vicinity of the optimum transition temperature is addressed. It is general consensus that in this region the electronic structure can no longer be described by Fermi liquid (FL) theory. Instead various other non-FL theories are discussed. A class of these models deals with reduced dimensionality in the CuO{sub 2}- planes, leading to Luttinger liquid like behaviour with spin and charge separation. Another route to one-dimensionality comes from the so called striped phase with spin and charge separation, unequivocally proven only for crystals of the LaSrCaCuO family. It is at present not clear, whether this instability is a prerequisite to the instability leading to superconductivity and whether a striped phase occurs for all cuprates. In ARPES measurements of Bi2201 with high angular and energy resolution a two-peak structure can be observed, which is dependent on the polarization of the incident light. It persists above T{sub c} and vanishes at a higher temperature. There are hints that this temperature corresponds to T{sup *}, the temperature where the pseudogap closes. Interestingly this two-peak structure is only visible along one CuO-bond direction. The comparison with a pseudo-1d-model directs interpretations of this feature towards a pseudo-1d-effect. The question is, if this can also be shown for double- layer compounds, making the observation of the splitting a more general feature of the cuprates. (author)}
place = {Poland}
year = {2004}
month = {Jul}
}
title = {Exploring the phase diagram of the Bi-cuprates by photoemission[Full text article has been submitted to the ''Journal of Alloys and Compounds'' (Elsevier)]}
author = {Janowitz, C}
abstractNote = {High temperature superconductivity is achieved by hole doping of parent compounds, which undergo a phase transition from the antiferromagnetic, insulating state to the metallic and superconducting state. This development can only be studied continuously on few members of the cuprate family: Bi{sub 2}Sr{sub 2}Ca{sub 1-x}Y{sub x}Cu{sub 2}O{sub 8+{delta}} single crystals, where the hole concentration in the two CuO{sub 2}-planes per unit cell (n=2) is controlled by the substitution of Ca by Y, and Bi{sub 2}Sr{sub 2}Ca{sub 1-} {sub x}La{sub x}CuO{sub 6+{delta}} single crystals, where this concentration in the one CuO{sub 2}-plane per unit cell (n=1) is controlled by the substitution of Sr by La enable this study of the doping dependence over a wide range of hole concentrations with ARPES. Investigations of antiferromagnetic parent compounds have so far mostly been reported for oxychlorides, like e.g. Sr{sub 2}CuO{sub 2}Cl{sub 2} and discussed within the t-t'-t'''-J model. Since the character of the CuO derived states near the Fermi level is decisive for the electronic structure, it will be discussed, whether this or other models like the generalized tight binding method (GTBM) give an appropriate description. A detailed treatment by this method with a five band Hubbard Hamiltonian, i.e. involving planar and off planar states of the CuO-planes shows, that the first removal state is composed not only from the Zhang-Rice singlet state but also from states with spin triplet character. In the second part of the talk the electronic structure for hole concentrations in the vicinity of the optimum transition temperature is addressed. It is general consensus that in this region the electronic structure can no longer be described by Fermi liquid (FL) theory. Instead various other non-FL theories are discussed. A class of these models deals with reduced dimensionality in the CuO{sub 2}- planes, leading to Luttinger liquid like behaviour with spin and charge separation. Another route to one-dimensionality comes from the so called striped phase with spin and charge separation, unequivocally proven only for crystals of the LaSrCaCuO family. It is at present not clear, whether this instability is a prerequisite to the instability leading to superconductivity and whether a striped phase occurs for all cuprates. In ARPES measurements of Bi2201 with high angular and energy resolution a two-peak structure can be observed, which is dependent on the polarization of the incident light. It persists above T{sub c} and vanishes at a higher temperature. There are hints that this temperature corresponds to T{sup *}, the temperature where the pseudogap closes. Interestingly this two-peak structure is only visible along one CuO-bond direction. The comparison with a pseudo-1d-model directs interpretations of this feature towards a pseudo-1d-effect. The question is, if this can also be shown for double- layer compounds, making the observation of the splitting a more general feature of the cuprates. (author)}
place = {Poland}
year = {2004}
month = {Jul}
}