Dielectric catastrophe at the magnetic field induced insulator to metal transition in Pr<Subscript>1-x</Subscript>Ca<Subscript>x</Subscript>MnO<Subscript>3</Subscript>(x = 0.30, 0.37) crystals

The dielectric permittivity and resistivity have been measured simultaneously as a function of magnetic field in Pr<Subscript>1-x</Subscript>Ca<Subscript>x</Subscript>MnO<Subscript>3</Sub script> crystals with different doping. A huge increase of dielectric permittivity was detected near percolation threshold. The dielectric and conductive properties are found to be mutually correlated throughout insulator to metal transition evidencing the dielectric catastrophe phenomenon. Data are analyzed in a framework of Maxwell-Garnett theory and the Mott-Hubbard theory attributed to the role of strong Coulomb interactions. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006