Muon spin relaxation studies of critical fluctuations and diffusive spin dynamics in molecular magnets

Francis Pratt, Tom Lancaster, Peter Baker, Stephen Blundell, Wakako Kaneko, Masaaki Ohba, Susumu Kitagawa, Seiko Ohira-Kawamura, Seishi Takagi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Systematic studies of magnetic critical exponents in local moment molecular magnets can be made by combining three different types of μ SR measurement; zero-field precession, longitudinal relaxation and the frequency shift in transverse field. Systems have been studied with 1D, 2D and 3D structures, having both simple and non-collinear magnetic interactions and the measurements have included investigation of the effect of chirality on the critical spin fluctuations. In the case of the model S = frac(1, 2) Heisenberg antiferromagnetic 1D chain Heisenberg antiferromagnetic quantum critical fluctuations suppress magnetic ordering and TCNQ radical ion salts can provide some excellent examples of this model. In particular, DEOCC-TCNQF4 behaves as a nearly ideal case with no ordering seen down to 20 mK even though the intrachain exchange interaction is 110 K. In contrast the DMTzNC-TCNQ compound orders at 1.5 K, but still shows evidence for significant residual quantum fluctuations in its ordered state in the form of a large suppression of the magnitude of the ordered part of the magnetic moment. From analysis of the characteristic field dependent muon relaxation behaviour as a function of temperature above the transition, the nature of the spin fluctuations is found to change as the transition is approached, suggesting a crossover either to 2D diffusion or to 1D ballistic motion.

Original languageEnglish
Pages (from-to)585-589
Number of pages5
JournalPhysica B: Condensed Matter
Volume404
Issue number5-7
DOIs
Publication statusPublished - Apr 15 2009
Externally publishedYes

Fingerprint

Spin dynamics
Spin fluctuations
spin dynamics
Magnets
muons
magnets
Chirality
Exchange interactions
Ballistics
Magnetic moments
Magnetization
Salts
Ions
precession
chirality
ballistics
frequency shift
crossovers
magnetic moments
retarding

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

Muon spin relaxation studies of critical fluctuations and diffusive spin dynamics in molecular magnets. / Pratt, Francis; Lancaster, Tom; Baker, Peter; Blundell, Stephen; Kaneko, Wakako; Ohba, Masaaki; Kitagawa, Susumu; Ohira-Kawamura, Seiko; Takagi, Seishi.

In: Physica B: Condensed Matter, Vol. 404, No. 5-7, 15.04.2009, p. 585-589.

Research output: Contribution to journalArticle

Pratt, F, Lancaster, T, Baker, P, Blundell, S, Kaneko, W, Ohba, M, Kitagawa, S, Ohira-Kawamura, S & Takagi, S 2009, 'Muon spin relaxation studies of critical fluctuations and diffusive spin dynamics in molecular magnets', Physica B: Condensed Matter, vol. 404, no. 5-7, pp. 585-589. https://doi.org/10.1016/j.physb.2008.11.123
Pratt, Francis ; Lancaster, Tom ; Baker, Peter ; Blundell, Stephen ; Kaneko, Wakako ; Ohba, Masaaki ; Kitagawa, Susumu ; Ohira-Kawamura, Seiko ; Takagi, Seishi. / Muon spin relaxation studies of critical fluctuations and diffusive spin dynamics in molecular magnets. In: Physica B: Condensed Matter. 2009 ; Vol. 404, No. 5-7. pp. 585-589.
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