Difficulty in the Fermi-Liquid-Based Theory for the In-Plane Magnetic Anisotropy in Untwinned High-T_c Superconductor

TL;DR

This paper critiques a recent Fermi-liquid theory for in-plane magnetic anisotropy in untwinned high-Tc superconductor YBCO, highlighting logical errors and parameter inconsistencies that question its validity.

Contribution

It identifies critical errors in the previous theory's assumptions and parameter choices, challenging its conclusions about magnetic anisotropy in YBCO.

Findings

Errors in the orthorhombicity parameter delta_0 undermine the theory's validity.

Inconsistent use of delta_0 in different publications casts doubt on the previous results.

The critique suggests the need for revised models to accurately describe magnetic anisotropy.

Abstract

Recently, Eremin and Manske [1] presented a oneband Fermi-liquid theory for the in-plane magnetic anisotropy in untwinned high-Tc superconductor YBa2Cu3O6:85 (YBCO). They claimed that they found good agreement with inelastic neutron scattering (INS) spectra. In this Comment, we point out that their conclusion on this important problem may be questionable due to an error in logic about the orthorhombicity delta_0 characterizing the lattice structure of YBCO. In Ref. [1], a single band at delta_0>0 is proved to be in accordance with the angle resolved photoemission spectroscopy (ARPES) on untwinned YBCO. But in their Erratum in PRL[3], they admit that delta_0= -0.03 was used to fit the INS data. Hence publications [1,3] contain errors that we believe invalidate their approach.