Journal Article

IMPULSE-2022-00080

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Magnetic field induced softening of spin waves and hard-axis order in the Kondo-lattice ferromagnet CeAgSb$_{2}$

Nikitin, S. E. ; Podlesnyak, A. ; Xu, J. (Corresponding author)MLZ* ; Voneshen, D. ; Le, M. D. ; Bud'ko, S. L. ; Canfield, P. C. ; Sokolov, D. A.

2021
Inst. Woodbury, NY

Please use a persistent id in citations: doi:10.1103/PhysRevB.104.115169

Abstract: A significant number of Kondo-lattice ferromagnets order perpendicular to the easy magnetization axisdictated by the crystalline electric field. The nature of this phenomenon has attracted considerable attention, butremains poorly understood. In the present paper we use inelastic neutron scattering supported by magnetizationand specific heat measurements to study the spin dynamics in the hard-axis ferromagnet CeAgSb2. In thezero-field state we observed two sharp magnon modes, which are associated with Ce ordering and extended up to≈3 meV with a considerable spin gap of 0.6 meV. Application of a magnetic field perpendicular to the momentdirection reduces the spectral intensity and suppresses the gap and significantly enhances the low-temperaturespecific heat at a critical field of Bc ≈ 2.8 T via a mean-field-like transition. Above the transition, in thefield-polarized state, the gap eventually reopens due to the Zeeman effect. We modeled the observed dispersionusing linear spin-wave theory taking into account the ground-state 6 doublet and exchange anisotropy. Ourmodel correctly captures the essential features of the spin dynamics including magnetic dispersion, distributionof the spectral intensity, as well as the field-induced behavior, although several minor features remain obscure.The observed spectra do not show significant broadening due to the finite lifetime of the quasiparticles. Alongwith a moderate electronic specific heat coefficient γ = 46 mJ/mol K2 this indicates that the Kondo couplingis relatively weak and the Ce moments are well localized. Altogether, our results provide profound insight intothe spin dynamics of the hard-axis ferromagnet CeAgSb2 and can be used as solid ground for studying magneticinteractions in isostructural compounds including CeAuSb2, which exhibits nematicity and unusual mesoscalemagnetic textures.

Keyword(s): Magnetic Materials (1st) ; Magnetism (2nd)

Note: ISSN 2469-9969 not unique: **2 hits**.

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Contributing Institute(s):

1. POLI (POLI)

Experiment(s):

1. Measurement at external facility

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; Clarivate Analytics Master Journal List ; Current Contents - Electronics and Telecommunications Collection ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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