Millimeter wave ESR measurement of diamond chain substance azurite

Abstract

Last decade, low dimensional quantum spin systems have attracted much attention since the discovery of the model substances. In this chapter, a new model substance of one-dimensional (ID) diamond chain is introduced. Most of the magnetic measurements of azurite were performed in '50-'60 year, and it is not considered as the model substance of diamond chain at that time. Therefore, in order to reveal the magnetic properties of the ID diamond chain, the millimeter and submillimeter wave ESR measurements of azurite single crystal have been performed. This chapter reports the results of the temperature dependence of azurite, and discusses the temperature dependence of line-width and g-value. Azurite CU3 (OH)2 (CO3 )2 is a candidate of the model substance for diamond chain with antiferromagnetic interaction. The millimeter and submillimeter wave ESR measurements of CU3 (OH)2 (CO3 )2 single crystal have been performed in the frequency region from 50GHz to 315GHz and in the temperature region from 4.2K to 80K. Very broad absorption lines are observed in the measured temperature region. The g-shift was observed below 20K, which is corresponds to a peak of the magnetic susceptibility. The decrease of line-width was observed below 3 OK. These temperature dependences are discussed in connection with the short range order.