On October 24, 2025, Santanu Mandal, PhD student in CRC LiMatI, successfully defended his doctoral thesis.
In his doctoral research, Santanu used extremely short, high-intensity laser pulses to explore how light can transform solid materials within just a few quadrillionths of a second.
The first part of his thesis investigates the insulator-to-metal transition in vanadium dioxide – a material that can rapidly change its electrical properties when heated or illuminated. Using visible light pulses lasting only 2.4 femtoseconds – less than a millionth of a billionth of a second – he was able to show that photoexcitation first drives the material into a fleeting metallic state before the atoms rearrange. These findings reveal that the transition is governed not only by electronic effects but also by strong atomic motions.
In the second part, Santanu developed a novel platform for studying high-harmonic generation (HHG) in solids, enabling broadband, phase-resolved detection of nonlinear optical responses. His experiments demonstrate that established models of strong-field physics break down in solids and must be replaced by new, more accurate theoretical descriptions.
His work provides valuable insights into ultrafast light–matter interactions, particularly at interfaces, where electronic and structural dynamics are closely intertwined.
CRC LiMatI warmly congratulates Santanu on this outstanding achievement and wishes him all the best for his future scientific endeavors.