相关论文: Spin-phonon coupling, q-dependence of spin excitat…
Band calculations show that a stripe-like anti-ferromagnetic spin wave is enforced by a 'half-breathing' phonon distortion within the CuO plane of HgBa_2CuO_4. This spin-phonon coupling is increased further by shear distortion and by…
The mechanism of spin-phonon coupling in high-T$_C$ copper oxides is explored from band calculations on La$_{(2-x)}$Sr$_x$CuO$_4$ and HgBa$_2$CuO$_4$ systems. The LMTO band calculations, based on the local density approximation, are made…
A theory for spin and lattice couplings to the electronic states in high-T$_C$ oxides is presented, with HgBa$_2$CuO$_4$ as an example. A simple analytical model suggests that the barrel band is sensitive to potential perturbations with…
A microscopic theory of spin excitations in strongly-correlated electronic systems within the t-J model is discussed. An exact representation for the dynamic spin susceptibility is derived. In the normal state, the excitation spectrum…
Effects of coupling between phonon distortions and stripe-like spin waves in the CuO plane of HgBa$_2$CuO$_4$ are studied by band calculations. Local exchange enhancements depend sensitively on the local structure around Cu sites.…
Band calculations on HgBa$_2$CuO$_4$ and La$_{(2-x)}$Sr$_x$CuO$_4$ with phonon and spin-waves within the CuO planes show that partial gaps are created at various energies depending on wavelengths. Spin and phonon gaps appear at different…
A strong electron-phonon interaction arises from the modulation of the superexchange interaction by phonons. As is studied in Phys. Rev. B 70, 184514 (2004), Cu-O bond stretching modes can be soft around (pm pi/a, 0) and (0, pm pi/a), with…
The mechanism of spin-phonon coupling (SPC) and possible consequencies for the properties of high-$T_C$ copper oxides are presented. The results are based on ab-initio LMTO band calculations and a nearly free-electron (NFE) model of the…
The large variations of T$_c$ across the cuprate families is one of the major unsolved puzzles in condensed matter physics, and is poorly understood. Although there appears to be a great deal of universality in the cuprates, several orders…
The quantum spin fluctuations of the S = 1/2 Cu ions are important in determining the physical properties of the high-transition temperature (high-Tc) copper oxide superconductors, but their possible role in the electron pairing for…
The excitations responsible for producing high-temperature superconductivity in the cuprates have not been identified. Two promising candidates are collective spin excitations and phonons. A recent argument against spin excitations has been…
The electron-phonon and spin-phonon coupling in typical high-T_C cuprates, like LSCO and HBCO are peaked for just a few q-vectors because of the 2-dimensional Fermi surface shape. The activation of few spin-phonon modes compensates for the…
We investigate the interplay of the electron-phonon and the spin fluctuation interaction for the superconducting state of YBa$_2$Cu$_3$O$_{7}$. The spin fluctuations are described within the nearly antiferromagnetic Fermi liquid theory,…
Previous theoretical studies on superconductivity were focused on the static states and adiabatic processes. Quantum mechanics simulations of time-dependent processes in superconductors were rarely performed previously. Here we use…
Using ultrafast optical techniques, we detect two types of bosons strongly coupled to electrons in the family of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ from the underdoped to overdoped regimes. The different doping dependences of the…
The strength of the electron-phonon coupling parameter and its evolution throughout a solid's phase diagram often determines phenomena such as superconductivity, charge- and spin-density waves. Its experimental determination relies on the…
The theory of electron-phonon interaction in the presence of strong correlation has been investigated in the present work. Due to the so called spin-charge separation, it is argued that the electron-phonon interaction in the strongly…
A strong electron-phonon interaction arises from the modulation of the superexchange interaction by lattice vibrations. It is responsible for the softening of the half-breathing modes around (pm pi/a,0) and (0, pm pi/a) in the…
We suggest that the phonon dispersion in cuprates becomes strongly anisotropic due to interaction with spin waves; moreover the phonon dispersion becomes singular along $|k_x|=|k_y|$ directions. This would allow more electrons to form…
First principle band calculations based on local versions of density functional theory (DFT), together with results from nearly free-electron models, can describe many typical but unusual properties of the high-$T_C$ copper oxides. The…