Interpocket polarization model for magnetic structures in rare-earth hexaborides

TL;DR

This paper introduces an interpocket polarization model explaining the magnetic structures in rare-earth hexaborides through Fermi surface interactions, supported by theoretical calculations and experimental spin-wave data analysis.

Contribution

It presents a novel interpocket polarization model linking Fermi surface features to magnetic structures, validated by experimental spin-wave spectrum analysis.

Findings

Interpocket polarization causes a maximum in I(q) around (1/4,1/4,1/2).

Model explains superstructures in Ce, Gd, Dy hexaborides.

Fitted I(q) from spin-wave data aligns with the model, indicating an A-type structure.

Abstract

The origin of peculiar magnetic structures in cubic rare-earth (R) hexaborides RB_6 is traced back to their characteristic band structure. The three sphere-like Fermi surfaces induce interpocket polarization of the conduction band as a part of a RKKY-type interaction. It is shown for the free-electron-like model that the interpocket polarization gives rise to a broad maximum in the intersite interaction I(q) around q=(1/4,1/4,1/2) in the Brillouin zone. This maximum is consistent with the superstructure observed in R=Ce, Gd and Dy. The wave-number dependence of I(q) is independently extracted from analysis of the spin-wave spectrum measured for NdB_6. It is found that I(q) obtained from fitting the data has a similarly to that derived by the interpocket polarization model, except that the absolute maximum now occurs at (0,0,1/2) in consistency with the A-type structure. The overall shape of I(q) gives a hint toward understanding an incommensurate structure in PrB_6 as well.