We present inelastic neutron scattering data on the quantum paramagnet AgVOAsO4 that establish the system is a S=1/2 alternating spin chain compound and provide a direct measurement of the spin gap. We also present experimental evidence for two different types of field-induced magnetic order between mu_0H_c1 = 8.4T and mu_0H_c2 = 48.9T, which may be related to Bose-Einstein condensation (BEC) of triplons. Thermodynamic measurements in magnetic fields up to 60T and temperatures down to 0.1K reveal a H-T phase diagram consisting of a dome encapsulating two ordered phases with maximum ordering temperatures of 3.8K and 5.3K respectively. This complex phase diagram is not expected for a single-Q BEC system and therefore establishes AgVOAsO4 as a promising multi-Q BEC candidate capable of hosting exotic vortex phases.
@article{arxiv.1902.04633,
title = {Field-induced double dome and Bose-Einstein condensation in the crossing quantum spin chain system AgVOAsO4},
author = {Franziska Weickert and Adam A. Aczel and Matthew B. Stone and V. Ovidiu Garlea and Chao Dong and Yoshimitsu Kohama and Roman Movshovich and Albin Demuer and Neil Harrison and Monika B. Gamza and Alexander Steppke and Manuel Brando and Helge Rosner and Alexander A. Tsirlin},
journal= {arXiv preprint arXiv:1902.04633},
year = {2019}
}