title: Observation of a level crossing in a molecular nanomagnet using implanted muons.
abstract: We have observed an electronic energy level crossing in a molecular nanomagnet (MNM) using muon spin relaxation. This effect, not observed previously despite several muon studies of MNM systems, provides further evidence that the spin relaxation of the implanted muon is sensitive to the dynamics of the electronic spin. Our measurements on a broken ring MNM [H(2)N(t)Bu(is)Pr][Cr(8)CdF(9)(O(2)CC(CH(3))(3))(18)], which contains eight Cr ions, show clear evidence for the S = 0 --> S = 1 transition that takes place at B(c) = 2.3 T. The crossing is observed as a resonance-like dip in the average positron asymmetry and also in the muon spin relaxation rate, which shows a sharp increase in magnitude at the transition and a peak centred within the S = 1 regime.
authors.affiliation: Clarendon Laboratory, Oxford University Department of Physics, Oxford, UK. t.lancaster1@physics.ox.ac.uk
authors.forename: T
authors.initials: T
authors.lastname: Lancaster
authors.forename: J S
authors.initials: JS
authors.lastname: Möller
authors.forename: S J
authors.initials: SJ
authors.lastname: Blundell
authors.forename: F L
authors.initials: FL
authors.lastname: Pratt
authors.forename: P J
authors.initials: PJ
authors.lastname: Baker
authors.forename: T
authors.initials: T
authors.lastname: Guidi
authors.forename: G A
authors.initials: GA
authors.lastname: Timco
authors.forename: R E P
authors.initials: RE
authors.lastname: Winpenny
mesh_terms: D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008280:Magnetics / Q000295:instrumentation*; D008422:Materials Testing; D008651:Mesons; D008956:Models, Chemical; D036103:Nanotechnology / Q000295:instrumentation*