Electronic nature of the lock-in magnetic transition in CeXAl4Si2

TL;DR

This study reveals the electronic and magnetic transition mechanisms in CeXAl4Si2 compounds, showing an incommensurate-to-commensurate magnetic transition driven by Fermi surface nesting, with implications for understanding Kondo lattice behaviors.

Contribution

It provides new insights into the magnetic transition mechanism in CeXAl4Si2, emphasizing the role of Fermi surface nesting over lattice distortion effects.

Findings

Incommensurate-to-commensurate magnetic transition at Tc = 9.19 K (Ce) and 10.75 K (Ir)

Spin density wave describes incommensurate phase correlations

Fermi surface nesting is identified as the primary mechanism behind the transition

Abstract

We have investigated the underlying magnetism in newly discovered single crystal Kondo lattices CeXAl4Si2, where X = Rh, Ir. We show that the compound undergoes an incommensurate-to-commensurate magnetic transition at Tc = 9.19 K (10.75 K in Ir). The spin correlation in the incommensurate phase is described by a spin density wave configuration of Ce-ions, which locks-in to the long-range antiferromagnetic order at T = Tc. The qualitative analysis of the experimental data suggests the role of the Fermi surface nesting, instead of the lattice distortion causing the Umklapp correction or the soliton propagation, as the primary mechanism behind this phenomenon.