1. Laboratory of Thermophysical and Tribological Properties, NaFoMat Group, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
2. Physics of Surfaces and Materials Unit, Tekniker, Basque Research and Technology Alliance (BRTA), C/Iñaki Goenaga 5, 20600 Eibar, Spain