Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet

TL;DR

This study investigates how magnetic excitations in a frustrated quantum antiferromagnet persist despite non-magnetic doping, revealing potential precursor states to a disordered magnetic phase.

Contribution

It demonstrates the robustness of singlet-triplet excitations in a doped frustrated antiferromagnet and identifies emergent low-energy fluctuations linked to disorder.

Findings

Singlet-triplet excitations persist across all doping levels studied.

Enhanced low-energy magnetic fluctuations at higher doping.

Potential evidence for a low-temperature random singlet phase.

Abstract

We present inelastic neutron scattering and thermodynamic measurements characterizing the magnetic excitations in a disordered non-magnetic substituted spin-liquid antiferromagnet. The parent compound Ba3Mn2O8 is a dimerized, quasi-two-dimensional geometrically frustrated quantum disordered antiferromagnet. We substitute this compound with non-magnetic vanadium for the S = 1 manganese atoms, Ba3(Mn1-xVx)2O8, and find that the singlet-triplet excitations which dominate the spectrum of the parent compound persist for the full range of substitution examined, x = 0.02 to 0.3. We also observe additional low-energy magnetic fluctuations which are enhanced at the greatest substitution values. These excitations may be a precursor to a low-temperature random singlet phase which may exist in Ba3(Mn1-xVx)2O8