Comment on "Doping Driven ($\pi,0$) Nesting and Magnetic Properties of Fe$_{1+x}$Te Superconductors" [Phys. Rev. Lett. 103, 067001 (2009)]

TL;DR

This paper critiques prior work on FeTe superconductors by demonstrating that the rigid-band approximation is invalid for describing disorder effects, and provides more accurate electronic structure calculations showing discrepancies in previous Fermi surface results.

Contribution

It introduces a detailed CPA-based analysis of disorder in FeTe alloys, challenging the validity of the rigid-band approximation used in earlier studies.

Findings

Rigid-band approximation is inadequate for FeTe alloys.

Previous energy shift estimates are inconsistent with CPA and FP-LMTO results.

Fermi surface of Fe_{1.063}Te in prior work is incorrect.

Abstract

In this Comment, using Korringa-Kohn-Rostoker coherent-potential approximation method in the atomic-sphere approximation (KKR-ASA CPA) to describe the effects of disorder due to excess Fe in FeTe alloys, we show that (i) the rigid-band approximation is inadequate to describe the effects of disorder and its application leads to an incorrect description of the underlying physics, (ii) the rigid-band energy shift of ~0.76 eV for going from FeTe to Fe_{1.068}Te (or Fe_{1.063}Te), as obtained by Han and Savrasov (Phys. Rev. Lett. 103, 067001(2009)), is inconsistent with our FP-LMTO as well as the KKR-ASA results, and thus the FS of Fe_{1.063}Te shown in Fig. 3(b) of their paper is not correct.