Towards understanding and controlling ultrafast dynamics in molecular photomagnets *

Manipulating magnetic materials is the cornerstone of hard drive technology. This modern information technology era has led to an explosive increase in the rate of data generation and storage creating an urgent need to achieve a new generation of faster and more efficient data storage devices. The development of ultrafast femtosecond lasers created the possibility to control the magnetic properties of materials using ultrashort pulses of light and therefore the study of ultrafast magnetisation dynamics has become one of the most active fields of magnetism driven by both fundamental and technological interest. However, a major challenge in this field is understanding the microscopic mechanisms responsible. Indeed, excited state dynamics initiated upon interaction with ultrashort laser pulses are characterised by a strong coupling between the electronic, vibrational and spin degrees of freedom. This is especially pertinent for the case of single-molecule magnets, which are the focus of this review, due to the high density of electronically excited states and the dense manifold of spin states within the energy range of interest. In this contribution, we discuss recent experimental and theoretical developments seeking to understand and control the ultrafast dynamics associated with molecular photomagnets and explore the new opportunities they offer as well as outlining some future developments required in this field.