Quantum electric dipole glass and frustrated magnetism near a critical point in Li2ZrCuO4

TL;DR

This study uncovers a unique interaction between quantum spin chains and electric dipoles in Li2ZrCuO4, revealing a glass-like electric dipole order that influences magnetic properties near a quantum critical point.

Contribution

It demonstrates the coexistence and interplay of electric dipole glass behavior and frustrated magnetism in Li2ZrCuO4, highlighting their impact on spiral spin states and multiferroicity.

Findings

Electric dipoles order glass-like at ~70 K

Electric dipole behavior influences magnetic exchange interactions

Potential renormalization of spiral spin structure

Abstract

We report a new peculiar effect of the interaction between a sublattice of frustrated quantum spin-1/2 chains and a sublattice of pseudospin-1/2 centers (quantum electric dipoles) uniquely co-existing in the complex oxide Li2ZrCuO4. 7Li nuclear magnetic-, Cu2+ electron spin resonance and a complex dielectric constant data reveal that the sublattice of Li+-derived electric dipoles orders glass like at Tg ~ 70 K yielding a spin site nonequivalency in the CuO2 chains. We suggest that such a remarkable interplay between electrical and spin degrees of freedom might strongly influence the properties of the spiral spin state in Li2ZrCuO4 that is close to a quantum ferromagnetic critical point. In particular that strong quantum fluctuations and/or the glassy behavior of electric dipoles might renormalize the exchange integrals affecting this way the pitch angle of the spiral as well as be responsible for the missing multiferroicity present in other helicoidal magnets.