Origin of “Hot Spots” in the pseudogap regime of Nd1.85Ce0.15CuO4: An LDA + DMFT + Σk study

Abstract

Material specific electronic band structure of the electron-doped high-Tc cuprate Nd1.85Ce0.15CuO4 (NCCO) is calculated within the pseudo gap regime, using the recently developed generalized LDA+DMFT+Σ k scheme. LDA/DFT (density functional theory within local density approximation) provides model parameters (hopping integral values, local Coulomb interaction strength) for the one-band Hubbard model, which is solved by DMFT (dynamical mean-field theory). To take into account pseudogap fluctuations LDA+DMFT is supplied with "external" k-dependent self-energy Σ k , which describes interaction of correlated conducting electrons with non-local Heisenberg-like antiferromagnetic (AFM) spin fluctuations responsible for pseudo gap formation. Within this LDA+DMFT+Σ k approach we demonstrate the formation of pronounced "hot-spots" on the Fermi surface (FS) map in NCCO, opposite to our recent calculations for Bi2Sr2CaCu2O 8−δ (Bi2212), which have produced rather extended region of FS "destruction". There are several physical reasons for this fact: (i) the "hot-spots" in NCCO are located closer to Brillouin zone center; (ii) correlation length of AFM fluctuations ξ is larger for NCCO; (iii) pseudogap potential ∆ is stronger, than in Bi2212. Comparison of our theoretical data with recent bulk sensitive high-energy angle-resolved photoemission (ARPES) data for NCCO provides good semiquantitative agreement. Based on that comparison alternative explanation of the van-Hove singularity at -0.3 eV is proposed. Optical conductivity both for Bi2212 and NCCO is also calculated within LDA+DMFT+Σ k and compared with experimental results, demonstrating satisfactory agreement.

The Fermi surface and the role of electronic correlations in Sm2−xCexCuO4

“…This question was addressed earlier by different groups [33,34]. Remarkably, their results on the Fermi surface contours for x ≈ 0.14 are very similar to our's in Fig.…”

ARPES spectral functions and Fermi surface for La1.86Sr0.14CuO4 compared with LDA + DMFT + Σk calculations

“…3 at panels (a) and (b) correspondingly. Both pictures reveal strong scattering around (π,0)-point which we associate with scattering in the vicinity of the so-called "hot-spots" (cross-points of a Fermi and AFM umklapp surfaces) which are close to the (π,0) 7,8 . Such strong scattering comes from scattering processes with momentum transfer of the order of Q=(π, π) 1,15 , corre- sponding to AFM pseudogap fluctuations.…”

“…The "hot-spots" are well observed in NCCO while towards the BZ border FS is almost restored as a non interacting one. 8 The present paper is devoted to pseudogap behavior in the underdoped LSCO and its comparison with Bi2212 and NCCO.…”

“…18 LDA+DMFT+Σ k method allowed us to obtain Fermi arcs and "hot-spots" behavior for both electron doped e.g. Nd was also discussed for B12212 7 and NCCO 8 .…”

ChemInform Abstract: Magnetic Mechanisms of Pairing in Strongly Correlated Electron System of Copper Oxides

“…That is why the correct band dispersion and spectral intensities for these systems cannot be obtained within LDA+DMFT. Natural extension of this method, LDA+cluster or cellular DMFT [14,15,16,17], LDA+DMFT+Σ k [18,19,20,21,22,23] and SDFT (spectral density functional theory) [24] provides momentum dependent self-energy and thus allow for the non-local correlations.…”