Competing Interactions and Magnetic Frustration in Yb4LiGe4

TL;DR

This study investigates the complex magnetic behavior of Yb4LiGe4, revealing a mesoscopically inhomogeneous magnetic state below 2 K driven by competing interactions, frustration, and enhanced two-dimensionality.

Contribution

It provides the first detailed experimental analysis of magnetic frustration and inhomogeneity in Yb4LiGe4, highlighting the effects of Li substitution on magnetic properties.

Findings

Presence of coexisting ferromagnetic and antiferromagnetic correlations.

Observation of a mesoscopically inhomogeneous magnetic state below 2 K.

Evidence of frustration effects and enhanced two-dimensionality.

Abstract

We have studied polycrystalline Yb4LiGe4, a ternary variant of the R5T4 family of layered compounds characterized by a very strong coupling between the magnetic and crystallographic degrees of freedom. The system is mixed valent, with non-magnetic Yb2+ and magnetic Yb3+ present, and is characterized by coexisting ferromagnetic and antiferromagnetic correlations. We present measurements of resistivity, AC-susceptibility, specific heat, and muon spin relaxation (muSR), below 1 K. The low temperature measurements suggest a transition to a mesoscopically inhomogeneous magnetically ordered state below 2 K characterized by fluctuations well below the ordering temperature. This unusual state is believed to result from the enhanced two-dimensionality produced by Li substitution and frustration effects inherent in the Yb sub-lattice geometry.