Hidden and coexistent magnetic phases in Kondo-type Cerium Hexaboride (CeB6)

TL;DR

This study uses electronic-structure calculations to explore the nearly degenerate magnetic and orbital phases in CeB6, revealing the importance of spin-orbit coupling and pressure effects on phase stability.

Contribution

It provides a detailed theoretical analysis of the magnetic and orbital phases in CeB6, highlighting the role of spin-orbit coupling and defect-induced pressure in phase stabilization.

Findings

Three magnetic phases are nearly degenerate energetically.

Spin-orbit coupling is crucial for reproducing experimental band structures.

Small pressures favor antiferromagnetic over ferromagnetic phases.

Abstract

The heavy fermion material CeB6 shows hidden magnetic ordered phases. Besides well-known Ferromagnetic(FM) and Antiferromagnetic(AFM) phases, CeB6 is speculated to form a unique antiferroquadrupolar (AFQ) phase that is orbital in nature. Hidden from many characterization methods that cannot assess orbital ordering, debate continue on the origins. From electronic-structure calculations, we find that these three phases are energetically almost degenerate, suggesting that magnetic domain walls form, possibly with defect boundaries. Only calculations with spin-orbit coupling reproduce most band structures and Fermi surfaces, as found in experiment, indicating the importance of crystal-field splitting. Simulated ionization peaks, i.e., Ce f0 and f1 states, also agree with photoemission data. Small pressures stabilizes the AFM over the FM phase, which is the observed phase at low temperature. We propose to realize such small physical pressure under various situations e.g. effect of intrinsic defects such as vacancies, antisites, surface effects etc.