Electronic Properties of Transuranium Compounds with HoCoGa$_5$-Type Tetragonal Crystal Structure

TL;DR

This study uses relativistic band calculations to analyze the electronic structures and Fermi surfaces of transuranium compounds with HoCoGa$_5$-type structure, revealing hybridization effects and similarities among different compounds.

Contribution

First detailed relativistic band structure analysis of transuranium compounds with HoCoGa$_5$-type structure, elucidating Fermi surface features and their relation to electron hybridization.

Findings

Fermi surfaces mainly due to 5f and Ga 4p hybridization.

Identification of cylindrical Fermi surface sheets in PuTGa$_5$.

Similarity of Fermi surfaces among Np, U, Pu, and Am compounds.

Abstract

By using a relativistic linear augmented-plane-wave method with the one-electron potential in the local-density approximation, we investigate energy band structures and the Fermi surfaces of transuranium compounds NpTGa$_5$, PuTGa$_5$, and AmCoGa$_5$ with transition metal atoms T. It is found in common that the energy bands in the vicinity of the Fermi level are mainly due to the large hybridization between $5f$ and Ga $4p$ electrons. For PuTGa$_5$, we observe several cylindrical sheets of Fermi surfaces with large volume for T=Co, Rh, and Ir. The de Haas-van Alphen (dHvA) frequencies are theoretically estimated for PuCoGa$_5$. It is also found that the Fermi surfaces of NpFeGa$_5$, NpCoGa$_5$, and NpNiGa$_5$ are similar to those of UCoGa$_5$, UNiGa$_5$, and PuCoGa$_5$, respectively, except for small details. For AmCoGa$_5$, the Fermi surfaces are found to consist of large cylindrical electron sheets and small closed hole sheets, similar to PuCoGa$_5$. The similarity is basically understood by the change of electron numbers inside the Fermi surfaces on the basis of a rigid-band picture. We discuss our theoretical Fermi surfaces with the dHvA experimental results on NpTGa$_5$.