Spin excitations in the quantum dipolar magnet Yb(BaBO$_3$)$_3$

TL;DR

This study investigates the magnetic properties and spin excitations in the quantum dipolar magnet Yb(BaBO$_3$)$_3$, revealing anisotropic behavior, absence of magnetic order down to very low temperatures, and evidence of dipolar interaction-driven spin dynamics.

Contribution

First detailed experimental characterization of spin excitations and magnetic anisotropy in Yb(BaBO$_3$)$_3$, highlighting the role of dipolar interactions in its quantum magnetic behavior.

Findings

No long-range magnetic order down to 0.27 K.

Observation of a Schottky anomaly indicating a ground-state doublet.

Field-dependent increase in spin excitations and relaxation rate.

Abstract

We report results of magnetization, specific-heat and muon-spin relaxation measurements on single crystals of disorder-free Yb$^{3+}$ triangular lattice Yb(BaBO$_3$)$_3$. The magnetization experiments show anisotropic magnetic properties with Curie-Weiss temperatures $\theta_{\perp}=-1.40$~K ($H \perp c$) and $\theta_{\parallel}=-1.16$~K ($H \parallel c$) determined from low temperature data. The absence of both long-range antiferromagnetic order and spin freezing is confirmed down to 0.27 K at zero field. A two-level Schottky anomaly due to the opening of the ground-state Kramers doublet is observed from the low-temperature specific-heat measurements when the applied magnetic fields $\mu_0H >0.7$~T. At zero field, the increase of both $C_{\rm mag}/T$ and the muon spin relaxation rate $\lambda$ below 1~K is due to the electronic spin excitations, which often exist in quantum magnets where dipole-dipole interaction creates an anisotropy of magnetic properties. The spin excitation is also supported by the unusual maximum of field dependence of $\lambda$ due to the field-induced increase of the density of excitations. We argue that dipolar interaction is dominant and induces the spin dynamics in the quantum magnet Yb(BaBO$_3$)$_3$.