Physical meaning and measurement of the entropic parameter q in an inhomogeneous magnetic systems

In this paper we present a thorough analysis of two systems magnetically inhomogeneous: the manganite La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3</S ubscript>/MgO and the amorphous alloy Cu<Subscript>90</Subscript>Co<Subscript>10</Subscript>. In both cases, the non-extensive statistics yield a faithful description of the magnetic behavior of the systems. In the model proposed here, the inhomogeneous magnetic system is composed by many Maxwell-Boltzmann homogeneous bits and the entropic parameter q is related to the moments of the distribution of the inhomogeneous quantity. From the analysis of Scanning Tunnelling Spectroscopy (STS) images, the q parameter can be directly measured. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006