相关论文: Fermi pockets and correlation effects in underdope…
The structural and electronic properties of La$_{2-x}$Ba$_x$CuO$_4$ were investigated as a function of Ba-concentration $0 \leq x \leq 1.2$, within the virtual crystal approximation (VCA) by means of first-principles total-energy…
Recent quantum oscillation experiments on SmB$_6$ pose a paradox, for while the angular dependence of the oscillation frequencies suggest a 3D bulk Fermi surface, SmB$_6$ remains robustly insulating to very high magnetic fields. Moreover, a…
Recent measurements of Fermi surface with de Haas-van Alphen oscillations in LaFePO showed a shrinking of the Fermi pockets with respect to first-principle LDA calculations, suggesting an energy shift of the hole and electrons bands with…
We argue that the results of recent scanning tunneling microscopy, angle-resolved photoemission and infrared spectroscopy experiments on the CuO chains of YBa$_2$Cu$_3$O$_{6+x}$ are consistently explained within a proximity model by the…
Charge-density wave order is now understood to be a widespread feature of underdoped cuprate high-temperature superconductors, although its origins remain unclear. While experiments suggest that the charge-ordering wavevector is determined…
The application of large magnetic fields ($B \sim B_{c2}$) to layered cuprates suppresses their high temperature superconducting behaviour and reveals competing ground states. In the widely-studied material YBa$_2$Cu$_3$O$_{6+x}$ (YBCO),…
We report an angular quantum oscillation study of Tl_2Ba_2CuO_{6+delta} for two different doping levels (Tc = 10K and 26 K) and determine the Fermi surface size and topology in considerable detail. Our results show that Fermi liquid…
Signatures of strong coupling effects in cuprate high-$T_{c}$ superconductors have been authenticated through a variety of spectroscopic probes. However, the microscopic nature of relevant excitations has not been agreed upon. Here we…
Pulsed NQR at the frequencies of 28-33 MHz has been used to study copper NQR spectra in YBa{2}Cu{3}O{7}, TmBa{2}Cu{3}O{7} and Y{0.9}Pr{0.1}Ba{2}Cu{3}O{7} compounds at temperatures of 4.2-200K. Quantitative analysis of the spectra has shown…
Quantum oscillations (QO) in metals refer to the periodic variation of thermodynamic and transport properties as a function of inverse applied magnetic field. QO frequencies are normally associated with semi-classical trajectories of Fermi…
A new phenomenological model is proposed to describe the evolution of the Fermi surface (FS) in a wide range of dopings. It reproduces the key features of the cuprates in the underdoped phase above the superconducting temperature $T_c$. It…
Recent inelastic neutron scattering measurements found that the spin susceptibility of detwinned and highly ordered ortho-II YBa_2Cu_3O_{6.5} exhibits, in both the normal and superconducting states, one-dimensional incommensurate…
The electronic states near the Fermi level of recently discovered superconductor Ba$_2$CuO$_{4-\delta}$ consist primarily of the Cu $d_{x^2-y^2}$ and $d_{3z^2-r^2}$ orbitals. We investigate the electronic correlation effect and the orbital…
An intact CuO$_2$ plane is widely believed to be a prerequisite for the high-$T_c$ superconductivity in cuprate superconductors. However, an exception may exist in the superconducting Ba$_2$CuO$_{3+\delta}$ materials where CuO chains play a…
We have reproduced band structure calculations from the literature and have used them to analyze in detail the energy landscape around the Fermi level. We found three Van Hove singularities, two below (-230, -54 meV) and one above the Fermi…
We present quantum oscillation measurements of YbRh2Si2 at magnetic fields above the Kondo-suppression scale H0 ~ 10 T. Comparison with electronic structure calculations is complicated because the "small" Fermi surface, where the Yb…
Recent experiments have revealed signatures of small Fermi pockets in the pseudogap phase of cuprate superconductors, most notably the Yamaji effect observed in $\mathrm{HgBa}_2\mathrm{CuO}_{4+\delta}$. The Yang-Rice-Zhang (YRZ) model…
The underdoped region of the cuprate's phase diagram displays many novel electronic phenomena both in the normal and the superconducting state. Many of these anomalous properties have found a natural explanation within the resonating…
Previously we showed the major effect of electron correlation in the cuprate superconductors is to lower the energy of the Cu d_x^2-y^2/O p_sigma (x^2-y^2) band with respect to the Cu d_z^2/O' p_z (z^2) band. In our 2D Hubbard model for…
This research aims to investigate the synergistic effect between charge density wave, selective electron-phonon coupling under antiferromagnetic fluctuations, as well as the unusual electron distribution observed in ARPES data in YBa2Cu3Ox…