Ultrafast dynamics in condensed matter: from 2D materials to molecular magnets
14:00 - 15:00
University of Edinburgh
CFEL (Bldg. 99)
The key to designing modern optoelectronic and magnetic functional materials lies in understanding how the charge carriers respond to the excitation on ultrafast timescales – tens or hundreds of femtoseconds. In this talk, I will introduce two projects which attempt to shed light on the fundamental processes behind the remarkable physics of two-dimensional materials and molecular magnets, and how we can control them.
The simplest way to fabricate few-layer
group 4 transition-metal dichalcogenides (TMDCs) samples is to mechanically
exfoliate them from bulk single crystals. High-quality films, however, are
often grown on supporting substrates, which can heavily modulate the behaviour
of the charge carries in the material. In this work, we look into the transient
band structure evolution of bilayer WS2 on a metallic substrate upon
pumping it with ultrafast laser pulses. We consider the relative effects of
substrate screening, interlayer interactions and surface quality on the
relaxation pathways available to hot electrons and holes.
Light-induced spin-state switching is a
prospective way to achieve faster magnetic data recording devices.
Molecule-based magnets are excellent candidates to implement this scheme since
they typically show rich photophysics that can be exploited by resonantly
exciting specific transitions, and their optical, electrical as well as magnetic
properties can be easily tuned through chemical substitutions. We investigate a
series of Prussian blue analogues (PBAs) to elucidate the dynamics of various
states involved in the superexchange interaction between the magnetic metal
centres in these compounds.