Origin of colossal dielectric response of Ca Cu3 Ti4 O12 studied by using CaTi O3 Ca Cu3 Ti4 O12 CaTi O3 multilayer thin films

To elucidate the origin of the colossal dielectric response (CDR) of Ca Cu3 Ti4 O12 (CCTO), multilayer thin films of CCTO interposed in insulating CaTi O3 (CTO) were synthesized using a pulsed laser deposition technique. The capacitance C of CTO/CCTO/CTO films with different layer thicknesses is measured. After removing the capacitance of CTO by extrapolating C to zero CTO thickness, the real part of dielectric constant of CCTO is estimated to be 329-435, which is much smaller than the reported value for CCTO thin films. This fact indicates that the CDR of CCTO is extrinsic and originates from an internal barrier layer capacitor.