He earned a PhD in March 1995 from the same University under the direction of Eduardo Lage, the title of the thesis was "Dynamics of spins systems".

Mendes was head of the Physics Department from December 2004 to February 2010 at University of Aveiro.

From October 2009 to February 2010 he was director of the Associated Laboratory of the Institute of Nanostructures, Nanomodelling and Nanofabrication (I3N) [1].

In 1996 he did a one year postdoctoral fellowship in Boston University under the supervision of Sid Redner.

He was invited as professor by Henri Poincaré University (Nancy), Universidade Federal Minas Gerais (UFMG) and Visiting Researcher at Consiglio Nazionale Delle Ricerche (Pisa), Nanyang Technological University (NTU), École Polytechnique Fédérale de Lausanne (EPFL-Lausanne) and ETH Zurich (Zurich).