Field and Polarization Dependent Quantum Spin Dynamics in Honeycomb Magnet Na$_2$Co$_2$TeO$_6$: Magnetic Excitations and Continuum

TL;DR

This study uses terahertz spectroscopy to explore how magnetic field and polarization influence quantum spin dynamics in Na$_2$Co$_2$TeO$_6$, revealing distinct regimes and a polarization-dependent continuum linked to quantum spin liquid behavior.

Contribution

It provides the first detailed polarization-dependent terahertz measurements of field-tuned quantum spin dynamics in a honeycomb magnet, uncovering new continuum features related to quantum spin liquid proximity.

Findings

Distinct spin dynamic regimes separated by critical fields

Polarization-dependent continuum observed in intermediate phase

Evidence of spin fluctuations related to quantum spin liquid

Abstract

We report terahertz spectroscopic measurements of quantum spin dynamics in the spin-1/2 honeycomb magnet Na$_2$Co$_2$TeO$_6$ as a function of applied magnetic field with different terahertz polarizations. Distinct field dependencies of the resolved spin dynamics are identified in three regimes, which are separated by two critical fields at $B_{c1}\approx 7$ and $B_{c2}\approx 10$ T. A polarization selective continuum is observed in the intermediate phase, featuring spin fluctuations of a proximate quantum spin liquid.