Theoretical investigation of TbNi_{5-x}Cu_x optical properties

TL;DR

This paper provides a theoretical analysis of the optical conductivity in the TbNi_{5-x}Cu_x series, revealing how Cu substitution affects electronic structure and optical properties, with results aligning well with experimental data.

Contribution

It introduces a detailed LSDA+U computational approach to study disorder effects and optical properties in TbNi_{5-x}Cu_x, highlighting the non-monotonic doping behavior of plasma frequency.

Findings

Optical conductivity structure diminishes with increased Cu content.

Optical intensity at 4 eV increases as Ni decreases.

Plasma frequency exhibits a maximum at x=1 due to competing effects.

Abstract

In this paper we present theoretical investigation of optical conductivity for intermetallic TbNi_{5-x}Cu_x series. In the frame of LSDA+U calculations electronic structure for x=0,1,2 and on top of that optical conductivities were calculated. Disorder effects of Ni for Cu substitution on a level of LSDA+U densities of states (DOS) were taken into account via averaging over all possible Cu ion positions for given doping level x. Gradual suppression and loosing of structure of optical conductivity at 2 eV together with simultaneous intensity growth at 4 eV correspond to increase of Cu and decrease of Ni content. As reported before [Knyazev et al., Optics and Spectroscopy 104, 360 (2008)] plasma frequency has non monotonic doping behaviour with maximum at x=1. This behaviour is explained as competition between lowering of total density of states on the Fermi level N(E_F) and growing of number of carriers. Our theoretical results agree well with variety of recent experiments.