The quantum magnet copper pyrazine dinitrate consists of isolated 1D chains of Cu2+ ions which each have spin- 1/2. Long range magnetic order is not expected to occur in an ideal 1D material, and no magnetic transition had been detected in copper pyrazine dinitrate. However, measurements using muons have recently shown that a transition to magnetic order does occur below 107 mK in this material. At these very low temperatures the interchain coupling, though weak, starts to have an effect and the system ‘realises’ that it is really three dimensional. Muons are very useful for detecting this effect and contrast with conventional bulk probes which are ineffective in very anisotropic systems and often miss the ordering transition.
T Lancaster, SJ Blundell, ML Brooks, PJ Baker (University of Oxford), FL Pratt (ISIS), JL Manson (Eastern Washington University, USA), CP Landee (Clark University), C Baines (Paul Scherrer Intitut, Switzerland)
Research date: December 2007
T. Lancaster et al., Phys. Rev. B 73 (2006) 020410