Electronic structure and nesting-driven enhancement of the RKKY interaction at the magnetic ordering propagation vector in Gd2PdSi3 and Tb2PdSi3

TL;DR

This study uses ARPES to reveal the Fermi surface of Gd2PdSi3 and Tb2PdSi3, linking electronic structure to magnetic ordering via RKKY interactions peaked at specific wave vectors.

Contribution

First ARPES measurements of these compounds' electronic structures, showing Fermi surface features that explain magnetic ordering through RKKY interaction enhancement.

Findings

Fermi surface consists of an electron barrel and spindle-shaped pockets

RKKY coupling peaks at the 1/2 GK wave vector

Magnetic order propagation vector matches Fermi surface features

Abstract

We present first-time measurements of the Fermi surface and low-energy electronic structure of intermetallic compounds Gd2PdSi3 and Tb2PdSi3 by means of angle-resolved photoelectron spectroscopy (ARPES). Both materials possess a flower-like Fermi surface consisting of an electron barrel at the G point surrounded by spindle-shaped electron pockets originating from the same band. The band bottom of both features lies at 0.5 eV below the Fermi level. From the experimentally measured band structure, we estimate the momentum-dependent RKKY coupling strength and demonstrate that it is peaked at the 1/2 GK wave vector. Comparison with neutron diffraction data from the same crystals shows perfect agreement of this vector with the propagation vector of the low-temperature in-plane magnetic order, thereby demonstrating the decisive role of the Fermi surface geometry in explaining the complex magnetically ordered ground state of ternary rare earth silicides.