Issue
EPL
Volume 83, Number 6, September 2008
Article Number 67002
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/83/67002
Published online 02 September 2008
EPL, 83 (2008) 67002
DOI: 10.1209/0295-5075/83/67002

Chain formation by spin pentamers in $\eta$-Na9V14O35

D. V. Zakharov1, H.-A. Krug von Nidda1, J. Deisenhofer1, F. Schrettle1, G. Obermeier2, S. Horn2 and A. Loidl1

1   Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg Universitätsstraße 2, 86135 Augsburg, Germany, EU
2   Experimentalphysik II, Institut für Physik, Universität Augsburg - Universitätsstraße 2, 86135 Augsburg, Germany, EU

Dmitri.Zakharov@physik.uni-augsburg.de

received 14 April 2008; accepted in final form 24 July 2008; published September 2008
published online 2 September 2008

Abstract
The nature of the gapped ground state in the quasi$\hbox{--} $one-dimensional compound $\eta$-Na9V14O35 cannot easily be understood, if one takes into account the odd number of spins on each structural element. Combining the results of specific heat, susceptibility and electron spin resonance measurements, we show that $\eta$-Na9V14O35 exhibits a novel ground state where multi-spin objects build up a linear chain. These objects —pentamers— consist of five antiferromagnetically arranged spins with effective spin 1/2. Their spatial extent results in an exchange constant along the chain direction comparable to the one in the high-temperature state.

PACS
76.30.-v - Electron paramagnetic resonance and relaxation.
65.40.Ba - Heat capacity.
75.10.Pq - Spin chain models.

© EPLA 2008