Quantum Tunneling in Half-Integer-Spin Kagome-Lattice Langasites

TL;DR

This study demonstrates persistent quantum tunneling-driven spin dynamics in samarium-based kagome-lattice Langasites, revealing universal scaling and an analogy with molecular nanomagnets, through muon spin relaxation and magnetization analysis.

Contribution

It provides the first evidence of quantum tunneling in half-integer-spin kagome-lattice Langasites, highlighting the role of anisotropic interactions and establishing a connection with molecular nanomagnets.

Findings

Persistent temperature-independent magnetic fluctuations down to lowest temperatures.

Quantum tunneling process attributed to pairwise anisotropic magnetic interactions.

Universal scaling of muon relaxation observed across different compounds.

Abstract

Employing the muon spin relaxation technique we evidence temperature independent magnetic fluctuations persisting down to the lowest temperatures in the samarium-based ($J=5/2$) kagome-lattice Langasite. A detailed bulk-magnetization characterization and comparison to the neodymium-based ($J=9/2$) compound allow us to assign the persistent spin dynamics to a quantum tunneling process. This is facilitated by pairwise anisotropic magnetic interactions, leading to a universal scaling of the muon relaxation. Our study reveals a remarkable analogy between weakly interacting half-integer-spin rare-earth magnets and molecular nanomagnets.