Chain formation by spin pentamers in η-Na₉V₁₄O₃₅

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

Corresponding author: Dmitri.Zakharov@physik.uni-augsburg.de

Received: 14 April 2008
Accepted: 24 July 2008

Abstract

The nature of the gapped ground state in the quasione-dimensional compound η-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 η-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.