Lecturer: Alon Ron
Abstract:
Interactions between electrons in solids are responsible for a wide variety of physical phenomena
such as magnetism, superconductivity Mott insulators and more. Understanding interactions
between electrons, and manipulating them to stabilize desired electronic phases have been the
research focus of the strongly correlated electrons community in the past few decades. Ultrafast
optics is a unique experimental tool where strong ultrashort pulses of light can be used both to
probe a multitude of electronic phenomena, and to excite and manipulate the properties of the
electronic system, driving it away from its equilibrium state. In this talk I will show how ultrafast
optical techniques can be used to probe spin spin correlations and modify magnetic interactions in
a Van der Waals ferromagnet. CrSiTe3 is composed of van der Waals bonded sheets of
ferromagnetically interacting Heisenberg spins that, in isolation, would be impeded from long range
order by the Mermin-Wagner theorem. I will show that CrSiTe3 evades thislaw via a two-step
crossover from two- to three-dimensional magnetic short range order above its Curie temperature
(Tc = 31 K), manifested through two previously undetected totally symmetric distortions at T2D ~ 110
K and T3D ~ 60 K serving as a direct probe for measuring intarlayer and interlayer spin-spin
correlations. Having understood the interplay between short range correlations and the magneto-
elastic distortions I will show how optically induced electron transfer could be used to enhance the
magnetic super-exchange interaction and how this manipulation can be detected by optically
probing generation of coherent phonons.