Unreachable glass transition in dilute dipolar magnet
2012 (English)In: Nature Communications, ISSN 2041-1723, Vol. 3, 857- p.Article in journal (Refereed) Published
In magnetic systems the combined effects of disorder and frustration may cause the moments to freeze into a disordered state at a spin-glass transition. Recent experiments have shown that the rare earth compound LiHo0.045Y0.955F4 freezes, but that the transition is unreachable because of dynamics that are 10(7) times slower than in ordinary spin-glass materials. This conclusion refutes earlier investigations reporting a speed-up of the dynamics into an exotic anti-glass phase caused by entanglement of quantum dipoles. Here we present a theory, backed by numerical simulations, which describes the material in terms of classical dipoles governed by Glauber dynamics. The dipoles freeze and we find that the ultra-slow dynamics are caused by rare, strongly ordered clusters, which give rise to a previously predicted, but hitherto unobserved, Griffths phase between the paramagnetic and spin-glass phases. In addition, the hyperfine interaction creates a high energy barrier to flipping the electronic spin, resulting in a clear signature in the dynamic correlation function.
Place, publisher, year, edition, pages
2012. Vol. 3, 857- p.
Ising Spin-Glasses, Disordered Magnet, Quantum, Relaxation, Phase, Dynamics, Lihof4
IdentifiersURN: urn:nbn:se:kth:diva-98336DOI: 10.1038/ncomms1857ISI: 000304611400052ScopusID: 2-s2.0-84864449821OAI: oai:DiVA.org:kth-98336DiVA: diva2:536906
QC 201206252012-06-252012-06-252012-06-25Bibliographically approved