1 Electronic nature of the enhanced conductivity in YSZ-STO multilayers deposited by PLD Andrea Cavallaro 1 , Mónica Burriel 2 , Jaume Roqueta 1 , Alexandra Apostolidis 1 , Alessandro Bernardi 1 , Albert Tarancón 3 , Srini Rajagopalan 4 , Stuart N. Cook 2 , Hamish L. Fraser 4 , John A. Kilner 2 , David W. McComb 2 and José Santiso 1,* 1 Centro de Investigación en Nanociencia y Nanotecnologia, CIN2 (CSIC-ICN). Campus UAB. 08193 Bellaterra, Spain 2 Dept. of Materials, Imperial College London, London SW7 2AZ, UK, 3 Institute for Microelectronics in Barcelona IMB-CNM (CSIC) Campus UAB. 08193 Bellaterra, Spain 4 Dept of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, USA. *corresponding author, e-mail: jsantiso@cin2.es Keywords: charge transport; thin films; interfaces; epitaxial heterostructures; ionic conductivity; PLD