Phase competition and anomalous thermal evolution in high-temperature superconductors

Abstract

The interplay of competing orders is relevant to high-temperature superconductivity known to emerge upon suppression of a parent antiferromagnetic order typically via charge doping. How such interplay evolves at low temperature-in particular at what doping level the zero-temperature quantum critical point (QCP) is located-is still elusive because it is masked by the superconducting state. The QCP had long been believed to follow a smooth extrapolation of the characteristic temperature T * for the strange normal state well above the superconducting transition temperature. However, recently the T * within the superconducting dome was reported to unexpectedly exhibit back-bending likely in the cuprate Bi2Sr2CaCu2O 8+δ . Here we show that the original and revised phase diagrams can be understood in terms of weak and moderate competitions, respectively, between superconductivity and a pseudogap state such as d-density-wave or spin-density-wave, based on both Ginzburg-Landau theory and the realistic t-t ′ -t ′′ -J-V model for the cuprates. We further found that the calculated temperature and doping-level dependence of the quasiparticle spectral gap and Raman response qualitatively agrees with the experiments. In particular, the T * back-bending can provide a simple explanation of the observed anomalous two-step thermal evolution dominated by the superconducting gap and the pseudogap, respectively. Our results imply that the revised phase diagram is likely to take place in high-temperature superconductors.

Variational Monte Carlo study of spin dynamics in underdoped cuprates

“…Although it has relatively higher energy upon doping, it has been long believed that DDW is the hidden order in the pseudogap state of cuprates 4,43 because Hamiltonian that stabilizes the d-wave superconductivity certainly stabilizes the DDW 44 . The competition between the DDW and superconductivity generates the back-bending behavior of the characteristic temperature of pseudogap under the superconducting dome 45 , in agreement with the recent ARPES measurements 46,47 and providing the simple explanation on the anomalous thermal evolution in cuprates 48,49 . In our previous work, we obtained an effective Hamiltonian similar to the DDW mean-field Hamiltonian after taking into account the effects of strong correlation and antiferromagnetic background 50 .…”

Ginzburg–Landau Theory for Flux Phase and Superconductivity in t–J Model

“…37,38) Since the GL theory derived microscopically directly reflects the electronic structure of the system, e.g., the shape of the Fermi surface that changes with doping, it can provide more useful information than that from phenomenological GL theories. 39,40) In order to discuss the above mentioned problems, numerical calculations that treat magnetic fields as well as the OPs self-consistently are necessary, and we will examine them in a separate study.…”

An extended antiferromagnetic model for quasielectrons in identical ionic-covalent bonds

“…I note that the multiple-component functions are introduced to develope the vector bundles [31][32][33]. While the hole components [9] do not appear in the density matrices in my ionic-covalent model, they may become important when both the particle-particle and particle-hole channels [47] are taken into account for the Bogoliubov-BCS quasiparticles. By considering the fractal structures [48] to extend such quasiparticles [9,49], in fact, we can obtain the form of Eq.…”