Spin Fluctuations and High-Temperature Superconductivity in Cuprates

Abstract

To describe the cuprate superconductors, models of strongly correlated electronic systems, such as the Hubbard or t-J models, are commonly employed. To study these models, projected (Hubbard) operators have to be used. Due to the unconventional commutation relations for the Hubbard operators, a specific kinematical interaction of electrons with spin and charge fluctuations emerges. The interaction is induced by the intraband hopping with a coupling parameter of the order of the kinetic energy of electrons W which is much larger than the antiferromagnetic exchange interaction J induced by the interband hopping. This review presents a consistent microscopic theory of spin excitations and superconductivity for cuprates where these interactions are taken into account within the Hubbard operator technique. The low-energy spin excitations are considered for the t-J model, while the electronic properties are studied using the two-subband extended Hubbard model where the intersite Coulomb repulsion V and electron-phonon interaction are taken into account.

Spin-wave excitations and magnetism of sputtered Fe/Au multilayers

“…On the other hand, the spin-wave excitations are also important parameters in magnetic systems [10][11][12], which play a crucial role on their magnetic properties at low temperature and they also describe the time scale for the magnetization dynamics. In this paper, the spin-wave excitations and thermal variation of the spontaneous magnetization in Fe/Au multilayers as a function of Fe thickness were studied and compared qualitatively and quantitatively with experimental results.…”

Superstripes in the Low Energy Physics of Complex Quantum Matter at the Mesoscale

“…There is a consensus that the high temperature superconductivity emerges in a landscape where nanoscale incommensurate charge density wave (ICDW) puddles of polaronic ICDW with the associated incommensurate periodic lattice distortions (PLD) in the CuO 2 atomic layer coexist with superconducting filamentary domains. The scenario where spin fluctuations mediate high temperature superconductivity has been discussed by Plakida [31], and Jalborg [32] has presented the minimal requirements of band structure electronic features for superconductivity.…”

“…Journal of Superconductivity and Novel Magnetism : Preface of the special issue for the Proceedings of Superstripes 2014 conference held in Erice, Italy on July [25][26][27][28][29][30][31]2014.…”

“…The most relevant advances on our understanding of the spatial and time fluctuations in heterostructures at atomic limit have been presented at the Superstripes -2014 conference, held in Erice, Italy on July [25][26][27][28][29][30][31]2014. A new low energy (in the range between 5 and 250 meV) physics focusing in the mesoscale (extending in the range between 10 and 100 microns) world is emerging.…”