ARPES experiments

More than 15 years studies of high temperature superconductivity in cuprates accumulated many evidences of the d-wave type symmetry of the superconducting order parameter (OP) in these materials. The most strong ones has been found from the ARPES experiments [1], quantum interference... 

The normalized angle dependent DoS, which is measured in ARPES experiments [Borisenko et al., 2002], can be obtained directly from (7) =... 

ARPES) experiments. Therefore, it is important to compare the above theory with ARPES data that reveal a sudden change ( kink ) in the Fermi (or group) velocity close to the Fermi level for all hole-doped cuprates. 

ARPES experiments have also been carried out in the insulating sulfur compound (TMTTF)2PFg (Fig. 20) and as expected [149], the charge gap is... 

The ARP experimental system employs a packed-bed column reactor through which the pretreatment liquid flows. Details of the reactor setup are described elsewhere [30]. ARP experiments were conducted under the following optimum set of conditions chosen for different feedstocks ... 

LL and HL Hybrid Poplar Substrate was first soaked overnight in 15% ammonia solution with solid to liquid ratio of 1 3.67 (w/w) before ARP experiment. The temperature of the reactor containing the soaked biomass was raised to 185 °C, and Dl water was passed for... 

A third technique, which has been proposed by Randeria et al. (1995), relies on the approximate sum rule relating the spectral function to the momentum space density of states (DOS), n(k). As noted in their letter, n(k) = f A(k,a))/((o)da). To see how this relates to what is measured in an ARPES experiment, note that, within the sudden approximation, a valence-band ARPES spectrum may be approximated as a sum over bands of the product of a matrix element for each band with the corresponding single band spectral function I k,a)) = Mn k,hv)f (0)A k,a)). It is... 

Experimental results are always crucial for any theory which aims to formulate basic physics behind observed phenomenon or property. However, an experiment always cover much wider variety of different influences which have impact on results of experimental observation than any theory can account for, mainly if theory is formulated on microscopic level and some unnecessary approximations and assumptions are usually incorporated. On the other hand, interpretation of many experimental results is based on particular theoretical model. This is also the case of ARPES experiments at reconstruction of Fermi surface for electronic structure determination of high-Tc cuprates. Interpretation of experimental results is based on band structure calculated for particular compound. Methods of band structure calculations are always approximate, with different level of sophistication. Calculated band structure, mainly its topology at EL, is a kind of reference frame for assignment of particular dispersion of energy distribution curve (EDC) or momentum distribution curve (MDC) to particular band of studied compound at interpretation of ARPES. This is in direct relation with theoretical understanding of crucial aspects of SC-state transition in general. 

With respect to topology of Cu-O chain band, as discussed above, this band should be the best candidate to be considered for gap opening in both, off-nodal (F-X, F-Y) and nodal (F-S) directions as seen in the ARPES results for YBCO [26]. One should stress, however, that also in case of gap opening in Cu-O chain band, expected d y2) symmetry is lost. More over, the authors [26] attribute the effects seen in the ARPES to bands of Cu-Oi planes and declare that in the spectra dispersion of Cu-O chain band is not present. There are a lot of experimental peculiarities of ARPES experiments with YBCO (twinning / untwining, surface... 

The data shown in Figure 3.2.2.26 demonstrate that ARPES experiments can provide information on the electronic structure in the liquid Pb film. In Figure 3.2.2.26b, the room temperature electronic stracture for this ML system is displayed, as measured along two high-symmetry azimuths within the surface BriUouin zone, F M and F K. A number of bands are visible, some of which are... 

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