Orbital-based Scenario for Magnetic Structure of Neptunium Compounds

TL;DR

This paper investigates the magnetic structures of neptunium compounds NpTGa_5 (T=Fe, Co, Ni) using an orbital-based model to explain experimental magnetic phase variations through numerical analysis.

Contribution

It introduces an effective two-orbital model based on j-j coupling to analyze and explain the magnetic phase diagram of neptunium compounds.

Findings

Identified various magnetic states including C-, A-, and G-type antiferromagnetic phases.

Provided an orbital-based explanation for the changes in magnetic structures among different compounds.

Used numerical techniques like exact diagonalization to analyze the phase diagram.

Abstract

In order to understand a crucial role of orbital degree of freedom in the magnetic structure of recently synthesized neptunium compounds NpTGa_5 (T=Fe, Co, and Ni), we propose to discuss the magnetic phase of an effective two-orbital model, which has been constructed based on a j-j coupling scheme to explain the magnetic structure of uranium compounds UTGa_5. By analyzing the model with the use of numerical technique such as exact diagonalization, we obtain the phase diagram including several kinds of magnetic states. An orbital-based scenario is discussed to understand the change in the magnetic structure among C-, A-, and G-type antiferromagnetic phases, experimentally observed in NpFeGa_5, NpCoGa_5, and NpNiGa_5.