Magnetic-field and doping dependence of low-energy spin fluctuations in the antiferroquadrupolar compound Ce(1-x)La(x)B(6)

Abstract

CeB(6) is a model compound exhibiting antiferroquadrupolar (AFQ) order, its magnetic properties being typically interpreted within localized models. More recently, the observation of strong and sharp magnetic exciton modes forming in its antiferromagnetic (AFM) state at both ferromagnetic and AFQ wave vectors suggested a significant contribution of itinerant electrons to the spin dynamics. Here we investigate the evolution of the AFQ excitation upon the application of an external magnetic field and the substitution of Ce with non-magnetic La, both parameters known to suppress the AFM phase. We find that the exciton energy decreases proportionally to T_N upon doping. In field, its intensity is suppressed, while its energy remains constant. Its disappearance above the critical field of the AFM phase is preceded by the formation of two modes, whose energies grow linearly with magnetic field upon entering the AFQ phase. These findings suggest a crossover from itinerant to localized spin dynamics between the two phases, the coupling to heavy-fermion quasiparticles being crucial for a comprehensive description of the magnon spectrum.

arXiv commentExtended version with a longer introduction and an additional figure. 6 pages and 5 figures

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Cited by in corpus (6)

• Multipolar phases and magnetically hidden order: Review of the heavy-fermion compound Ce(1-x)La(x)B6
• Field-angle resolved magnetic excitations as a probe of hidden-order symmetry in CeB6
• Doping-induced redistribution of magnetic spectral weight in substituted hexaborides Ce${}_{1-x}$La${}_x$B${}_6$ and Ce${}_{1-x}$Nd${}_x$B${}_6$
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• Magnetic field dependence of the neutron spin resonance in CeB6
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