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arXiv:1902.04633 · Physical review. B./Physical review. B

Field-induced double dome and Bose-Einstein condensation in the crossing quantum spin chain system AgVOAsO4

Franziska Weickert, A. A. Aczel, M. B. Stone, Vasile Ovidiu Garlea, Chao Dong, Yoshimitsu Kohama, Roman Movshovich, A. Demuer, N. Harrison, Monika Gamża, Alexander Steppke, M. Brando, Helge Rosner, Alexander A. Tsirlin

Published Sep 17, 2019• 17 citations
arXivHTMLPDF

Abstract

We present inelastic neutron-scattering data on the quantum paramagnet ${\mathrm{AgVOAsO}}_{4}$ that establish this system as a $S=1/2$ alternating spin chain compound and provide a direct measurement of the spin gap $\mathrm{\ensuremath{\Delta}}=1.2\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$. We also present experimental evidence for two different types of field-induced magnetic order between ${\ensuremath{\mu}}_{0}{H}_{c1}=8.4\phantom{\rule{0.16em}{0ex}}\mathrm{T}$ and ${\ensuremath{\mu}}_{0}{H}_{c2}=48.9\phantom{\rule{0.16em}{0ex}}\mathrm{T}$, which may be related to Bose-Einstein condensation (BEC) of triplons. Thermodynamic measurements in magnetic fields up to 60 T and temperatures down to 0.1 K reveal a $H\ensuremath{-}T$ phase diagram consisting of a dome encapsulating two ordered phases with maximum ordering temperatures of 3.8 and 5.3 K, respectively. This complex phase diagram is not expected for a single-$\stackrel{P\vec}{Q}$ BEC system and therefore establishes ${\mathrm{AgVOAsO}}_{4}$ as a promising multi-$\stackrel{P\vec}{Q}$ BEC candidate capable of hosting exotic vortex phases.

DOI
10.1103/physrevb.100.104422

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We present inelastic neutron-scattering data on the quantum paramagnet AgVOAsO4{\mathrm{AgVOAsO}}_{4}AgVOAsO4​ that establish this system as a S=1/2S=1/2S=1/2 alternating spin chain compound and provide a direct measurement of the spin gap \ensuremathΔ=1.2meV\mathrm{\ensuremath{\Delta}}=1.2\phantom{\rule{0.16em}{0ex}}\mathrm{meV}\ensuremathΔ=1.2meV. We also present experimental evidence for two different types of field-induced magnetic order between \ensuremathμ0Hc1=8.4T{\ensuremath{\mu}}_{0}{H}_{c1}=8.4\phantom{\rule{0.16em}{0ex}}\mathrm{T}\ensuremathμ0​Hc1​=8.4T and \ensuremathμ0Hc2=48.9T{\ensuremath{\mu}}_{0}{H}_{c2}=48.9\phantom{\rule{0.16em}{0ex}}\mathrm{T}\ensuremathμ0​Hc2​=48.9T, which may be related to Bose-Einstein condensation (BEC) of triplons. Thermodynamic measurements in magnetic fields up to 60 T and temperatures down to 0.1 K reveal a H\ensuremath−TH\ensuremath{-}TH\ensuremath−T phase diagram consisting of a dome encapsulating two ordered phases with maximum ordering temperatures of 3.8 and 5.3 K, respectively. This complex phase diagram is not expected for a single-\stackrel{P\vec}{Q} BEC system and therefore establishes AgVOAsO4{\mathrm{AgVOAsO}}_{4}AgVOAsO4​ as a promising multi-\stackrel{P\vec}{Q} BEC candidate capable of hosting exotic vortex phases.
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