Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFermi Surface of Metallic V$_2$O$_3$ from Angle-Resolved Photoemission: Mid-level Filling of $e_g^{pi}$ Bands
60
0
0.0
(
0
)
Added by
Jonathan D. Denlinger
Publication date
2016
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Using angle resolved photoemission spectroscopy (ARPES) we report the first band dispersions and distinct features of the bulk Fermi surface (FS) in the paramagnetic metallic phase of the prototypical metal-insulator transition material V$_2$O$_3$. Along the $c$-axis we observe both an electron pocket and a triangular hole-like FS topology, showing that both V 3$d$ $a_{1g}$ and $e_g^{pi}$ states contribute to the FS. These results challenge the existing correlation-enhanced crystal field splitting theoretical explanation for the transition mechanism and pave the way for the solution of this mystery.
rate research
Read More
We have performed soft-X-ray angle resolved photoemission for metallic V$_2$O$_3$. Combining a micro focus beam (40 x 65 ${mu}$m$^2$) and micro positioning techniques with a long working distance microscope, we have succeeded in observing band dispersions from tiny cleavage surfaces with typical size of the several tens of ${mu}$m. The photoemission spectra show a clear position dependence reflecting the morphology of the cleaved sample surface. By selecting high quality flat regions on the sample surface, we have succeeded in band mapping using both photon-energy and polar-angle dependences, opening the door to three-dimensional ARPES for typical three dimensional correlated materials where large cleavage planes are rarely obtained.
A recent letter by Xue et al. (PRL v.83, 1235 (99)) reports a Fermi-Liquid (FL) angle resolved photoemission (ARPES) lineshape for quasi one-dimensional Li0.9Mo6O17, contradicting our report (PRL v.82, 2540 (99)) of a non-FL lineshape in this material. Xue et al. attributed the difference to the improved angle resolution. In this comment, we point out that this reasoning is flawed. Rather, we find that their data have fundamental differences from other ARPES results and also band theory.
The connection between the Fermi surface and charge-density wave (CDW) order is revisited in 2H-TaSe2. Using angle-resolved photoemission spectroscopy, ab initio band structure calculations, and an accurate tight-binding model, we develop the empirical k-resolved susceptibility function, which we use to highlight states that contribute to the susceptibility for a particular q-vector. We show that although the Fermi surface is involved in the peaks in the susceptibility associated with CDW order, it is not through conventional Fermi surface nesting, but rather through finite energy transitions from states located far from the Fermi level. Comparison with monolayer TaSe2 illustrates the different mechanisms that are involved in the absence of bilayer splitting.
High resolution angle-resolved photoemission measurements have been carried out on (Sr,K)Fe$_2$As$_2$ superconductor (Tc=21 K). Three hole-like Fermi surface sheets are clearly resolved for the first time around the Gamma point. The overall electronic structure shows significant difference from the band structure calculations. Qualitative agreement between the measured and calculated band structure is realized by assuming a chemical potential shift of -0.2 eV. The obvious band renormalization suggests the importance of electron correlation in understanding the electronic structure of the Fe-based compounds.
We report on the results of angle-resolved photoemission experiments on a quasi-one-dimensional $MX$-chain compound [Ni(chxn)$_2$Br]Br$_2$ (chxn = 1$R$,2$R$-cyclohexanediamine), a one-dimensional Heisenberg system with $S=1/2$ and $J sim 3600$ K, which shows a gigantic non-linear optical effect. A band having about 500 meV energy dispersion is found in the first half of the Brillouin zone $(0le kb/pi <1/2)$, but disappears at $kb / pi sim 1/2$. Two dispersive features, expected from the spin-charge separation, as have been observed in other quasi-one-dimensional systems like Sr$_2$CuO$_3$, are not detected. These characteristic features are well reproduced by the $d$-$p$ chain model calculations with a small charge-transfer energy $Delta$ compared with that of one-dimensional Cu-O based compounds. We propose that this smaller $Delta$ is the origin of the absence of clear spin- and charge-separation in the photoemission spectra and strong non-linear optical effect in [Ni(chxn)$_2$Br]Br$_2$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
