Comment to the paper "In-plane spectral weight shift of charge-carriers in YBa2Cu3O(6.9)" by A. V. Boris et al., Science 304, p. 708 (2004)

TL;DR

This paper critiques a previous study claiming spectral weight transfer in cuprates during superconductivity, arguing that their analysis is flawed and that existing data supports an increase in intraband spectral weight.

Contribution

It provides a critical analysis showing that the original data actually supports an increase in intraband spectral weight, challenging prior claims of spectral weight decrease during superconductivity.

Findings

Original data supports increase in intraband spectral weight.

Analysis flaws in the criticized paper are identified.

Supports transfer of spectral weight from high to low frequencies.

Abstract

Recently, A. V. Boris and colleagues claimed to deduce a decrease of intraband spectral weight (SW), and a transfer of SW from intraband to inter-band frequencies, when optimally-doped or slightly underdoped cuprates become superconducting [A. V. Boris et al., Science 304, p. 708 (2004)]. We show that, while their data agree with others [H. J. A. Molegraaf et al., Science 295, p. 2239 (2002) ; A.F. Santander-Syro et al., Europhys.Lett 62, p. 568 (2003)], their analysis is flawed. They cannot disprove the results which yield a superconductivity-induced increase of intraband SW, and a transfer of SW from high to low frequencies, in underdoped or nearly optimally doped Bi-2212.