Angle-resolved photoemission study of USb2 the 5f band struc(7)

Single crystal antiferromagnetic USb2 was studied at 15K by angle-resolved photoemission with an overall energy resolution of 24 meV. The measurements unambiguously show the dispersion of extremely narrow bands situated near the Fermi level. The peak at th

below the Fermi level the electronic band structure of USb2 is dominated by U6d and U5f states.

The normal emission PES spectra measured for hν = 34 eV (Fig.2a) shows one sharp feature situated near the Fermi edge. The rest of the spectrum remains completely flat, which is an evidence of a very clean, high quality sample surface resulting in very well defined incidence and emission angles. The peak near the Fermi edge, which was interpreted so far as the U5f-conduction band hybridized narrow band, changes its position from 37 meV for θ = 00 to 23 meV for θ = 60 and 70 giving evidence of a 14 meV dispersion (Fig. 2b). For θ = 50 the FWHM of this peak starts growing from 24 meV for lower angles, up to 48 meV for θ = 70. The given FWHM values include the instrumental resolution and thus the natural line width is extremely sharp (as demonstrated in the detailed analysis of Fig.1). When fitting the data we use a Gaussian function for experimental resolution and a Lorentzian function for the natural line width. For θ = 80 and 90 we see two structures in the Fermi level region. It appears that the increase in width away from normal is a result of two states with different dispersions.

A large dispersion (about 270 meV) is shown in the structure marked as

B in Fig. 2b, which appears at 470 meV below the Fermi level for θ = 40. The intensity of this structure grows gradually up to θ = 90, whereas the binding energy shifts downwards and for θ = 90 it is situated at 200 meV.

The PES spectra taken for hν = 43 eV (Fig.3) also shows dispersion of peak A, which changes the energy position from 34 meV (θ = 00) to 48 meV (θ = 60). We can not see two peaks for θ = 60, but the FWHM is almost twice of that for θ = 50, which suggests an additional contribution for higher angles. The structure B appears for θ = 20 at a binding energy of 410 meV and changes its binding energy position to 234 meV for θ = 60.

Photoemission data for hν = 60 eV (Fig.4) show both A and B structures even in the normal emission spectrum. The dispersion of peak A in this case is 14 meV, the A position for θ = 00 is 67 meV and for θ = 100 is 81 meV below E F. The structure B is

7

百度搜索“77cn”或“免费范文网”即可找到本站免费阅读全部范文。收藏本站方便下次阅读，免费范文网，提供经典小说教育文库Angle-resolved photoemission study of USb2 the 5f band struc(7)在线全文阅读。