Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: CE: Low-dimensional Systems - Materials 1

TT 5.5: Vortrag

Montag, 22. März 2010, 15:15–15:30, H18

Magnetism in Azurite Studied by Muon Spin Rotation — Mathias Kraken¹, Josefin Engelke¹, Stefan Süllow¹, •Jochen Litterst¹, Anja Wolter², Bernd Wolf³, Michael Lang³, Chris Baines⁴, and Hubertus Luetkens⁴ — ¹IPKM, Technische Universität Braunschweig, Braunschweig, Germany — ²IFW , Dresden, Germany — ³Physikalisches Institut, Universität Frankfurt, Frankfurt am Main, Germany — ⁴LEM, PSI, Villigen, Switzerland

The natural mineral azurite Cu₃(CO₃)₂(OH)₂ represents a new type of low-dimensional frustrated quantum spin system with a diamond spin chain as basis. From specific heat [1] there is evidence for a phase transition at ca. 1.8 K which however is magnetically still ill-defined. Earlier muon spin rotation experiments [2] have indicated a magnetic transition yet no systematic study has been reported. We have performed zero field and transverse field muon spin rotation experiments at Paul Scherrer Institut Villigen (Switzerland) in the temperature range from 0.02 K to 6 K on polycrystalline powder and a single crystal. We could corroborate the appearance of magnetic order below 1.9 K from spontaneous muon spin rotation with a frequency following a magnetization curve. The rotation profile is indicative of a modulated spin structure. In addition we find a pre-cursor phase between 1.9 K and about 3 K which we relate to the onset of magnetic correlations between Cu monomers via dimers.

[1] H. Kikuchi, et al., Phys. Rev. Lett. 94 (2005) 227201.

[2] H. Kikuchi, et al., Progress of Theoretical Physics Supplement. 159 (2005)1 2005