: An unusual low-dimensional quantum magnet

✍ Scribed by J.L. Gavilano; E. Felder; D. Rau; H.R. Ott; P. Millet; F. Mila; T. Cichorek; A.C. Mota

• Book ID: 104079622
• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 106 KB
• Volume: 378-380
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2006.01.261

✦ Synopsis

Results of present and previous measurements of the 23 Na NMR response, dc-and ac-magnetic susceptibilities and the specific heat of Na 2 V 3 O 7 at low temperatures suggest that this material is close to a quantum critical point (QCP) at m 0 H ¼ 0 T. The experimental data can be explained by assuming that below 100 K the localized V magnetic moments ðS ¼ 1 2 Þ form a collection of dimers, with a broad distribution of singlet-triplet gaps. Most of the dimers adopt a singlet ground state with gaps between 0 and 350 K. A small fraction of them forms triplet ground states with gaps between 0 and 15 K. The degeneracy of the triplet ground states is lifted by a phase transition at an unusually low temperature of 0.086 K. Modest magnetic fields effectively quench this low-temperature state and the system is driven away from the QCP as the applied fields are enhanced to above 1 T.