Growth of the optical conductivity in the Cu-O planes

Abstract

The Rapid Communications section is intended for the accelerated publication of important new results g. ince manuscripts submitted to this section are given priority treatment both in the editorial once and in production, authors sltould explain in their submittal letter why the work justiftes this special handling A. Rapid Communication should be no longer titan 3' printed pages and must be accompanied by an abstract Pa.ge proofs are sent to authors, but, because of the accelerated schedule, publication is not delayed for receipt of corrections unless requested by the author or noted by tile editor

Violation of an f -sum rule with generalized kinetic energy

“…In normal metals, when ω c is chosen to be in the region of the optical gap, N eff is simply given by the number of electrons in the conduction band. However, in the cuprates [2,3], N eff deviates from what one expects from the dopant concentration, x. When 0 < x < 0.2, instead of having N eff (x) = x, N eff (x) is greater than x and is concave downward.…”

“…On the other hand, in the low temperature and high density regime, the sum rule is proportional 2 We ignore the fact that the kinetic energy of our model is rotationally invariant and simply replace it by the band dispersion. 3 The sum rule in this case is usually written as…”

“…This model is equivalent to the restricted band model where the kinetic energy is replaced by the band dispersion, E(p). 2 In the restricted band model, one considers only particles in a single band and ignores the inter-band interactions. It turns out that the conductivity sum rule of the restricted band model [4,12], is given by…”

Pseudogap in Doped Mott Insulators is the Near-Neighbor Analogue of the Mott Gap

“…Band insulators possess rigid bands and hence doping only creates quasiparticles at the Fermi level. That this picture fails fundamentally in the parent cuprates, which are all antiferromagnetic Mott insulators, is immediately evident from optical conductivity experiments [1,2] which reveal that even for T ≫ T N , a gap of order 2eV exists and doping leads to a massive reshuffling of spectral weight from 2eV to the Fermi energy. These experiments lay plain that what is missing in the antiferromagnetic reduction is Mottness itself: 1) in the absence of magnetic ordering (T > T N ), a charge gap exists in the single particle spectrum, 2) each electronic state in the first Brillouin zone has spectral weight both above and below the charge gap, and 3) the sum rule that each singleparticle state carries unit weight is satisfied [3] only when the spectral function is integrated across the charge gap not simply up to the chemical potential as in a band insulator.…”

Use of x-ray scattering functions in Kramers-Kronig analysis of reflectance

“…Many reports of Kramers-Kronig analysis of reflectance have appeared, spanning more than 50 years, 7 with studies of metals, [8][9][10][11][12][13][14][15] pure and doped elemental solids, [16][17][18] organic conductors, [19][20][21] charge-density-wave materials, [22][23][24] conducting polymers, [25][26][27] cuprate superconductors, [28][29][30][31][32][33][34][35][36][37][38] manganites, [39][40][41] pnictides, [42][43][44][45][46][47][48] heavy-Fermions, 49 multiferroics, [50][51][52][53] topological insulators, [54][55][56] and many others. In addition, a number o...…”