Magnetic properties and field-induced phenomena in the Jeff = 1/2 distorted kagome antiferromagnet

TL;DR

This study investigates the magnetic properties and field-induced phenomena in a rare-earth kagome antiferromagnet with Jeff=1/2, revealing complex magnetic ordering, quantum criticality, and potential for exotic quantum states driven by frustration and spin-orbit coupling.

Contribution

It provides a comprehensive experimental analysis of magnetic behavior, phase transitions, and quantum critical phenomena in a Jeff=1/2 distorted kagome antiferromagnet, highlighting the role of competing states.

Findings

Presence of two energy scales consistent with INS results.

Observation of a 1/3 magnetization plateau at low temperatures.

Evidence of a field-induced quantum critical point.

Abstract

The intertwining between competing degrees of freedom, anisotropy, and frustration-induced quantum fluctuations offers an ideal ground to realize exotic quantum phenomena in the rare-earth-based kagome lattice. The magnetic susceptibility reveals the presence of two energy scales in agreement with the INS results. The higher energy state is dominated by CEF excitations, where the lowest Kramers ground-state doublet is well separated from the excited state suggesting that the compound realizes a low-energy state at low temperatures. The second energy scale is witnessed via thermodynamic results that reveal an anomaly at 0.3 K typical of a phase transition, which is attributed to the presence of complex magnetic ordering phenomena. The broad maximum in the specific heat well above 0.3 K indicates the presence of short-range spin correlations that is corroborated by muon spin relaxation rate results. The isothermal magnetization reveals a field-induced 1/3 magnetization plateau at low temperatures. muSR relaxation rate experiments, on the other hand, neither show the signature of a phase transition nor spin-freezing down to 34 mK. The ZF muSR relaxation is governed by the Orbach process and reveals the presence of a fluctuating state owing to the depopulation of crystal field levels reflected as a constant value of relaxation rate in the temperature range 0.4-10 K. NMR results indicate the presence of fluctuating Nd3+ moments down to 1.8 K consistent with muSR experiments. Our comprehensive results reveal that a field-induced quantum critical phenomenon is at play in this frustrated kagome magnet and enable us to construct a phase diagram exemplifying the proximity effect of competing magnetic states. This sets the stage to investigate the broad RE3BWO9 family of rare-earth kagome magnets promising to host exotic quantum states driven by spin-orbit coupling and geometrical frustration.