Crystal field excitation in the chiral helimagnet YbNi${}_3$Al${}_9$

Abstract

Crystal field level scheme of a uniaxial chiral helimagnet YbNi${}_3$Al${}_9$, exhibiting a chiral magnetic soliton lattice state by Cu substitution for Ni, has been determined by inelastic neutron scattering. The ground and the first excited doublets are separated by 44 K and are simply expressed as $\alpha |\pm 7/2⟩+\beta |\mp 5/2⟩$ with $\alpha$ and $\beta$ nearly equal to $\pm 1/\sqrt{2}$. The easy axis of the crystal field anisotropy is the $c$ axis when the excited levels are populated at high temperatures and high magnetic fields. On the other hand, the magnetism at low temperatures and low magnetic fields, where only the ground doublet is populated, is described by an easy plane anisotropy which may be treated as an $S=1/2$ system with an anisotropic $g$-factor, $g_{xy}=3.02$ and $g_z=1.14$. An orbital dependent exchange interaction is also discussed to explain the temperature dependence of the magnetic susceptibility based on this level scheme.

arXiv comment9 pages, 7 figures, 2 figures in the supplemental material, accepted for publication in Phys. Rev. B

References in corpus (5)

• Finite-Temperature Properties of Three-Dimensional Classical Chiral Helimagnets
• Chiral Soliton Lattice Formation in Monoaxial Helimagnet Yb(Ni${}_{1-x}$Cu${}_x$)${}_3$Al${}_9$
• Determining the in-plane orientation of the ground-state orbital of CeCu2Si2
• Dynamics of the Singlet-Triplet System Coupled with Conduction Spins -- Application to Pr Skutterudites
• Magnetic anisotropy of chiral magnet Yb(Ni${}_{1-x}$Cu${}_x$)${}_3$Al${}_9$ at high magnetic fields

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