All events are in Central time unless specified.
Seminar

Graduate Student Seminar

Date:
Time:
12:30 pm
Jorgensen Hall Room: 145
Note that this event is only for graduate students.

Presenter: Paulo Costa
Title and abstract:
Optically Switchable Magnets
Using X-rays to induce spin crossover transitions at room temperature

Spin crossover molecules are able to transition between ferromagnetic (high spin) and paramagnetic (low spin) states in response to various external stimuli. This specific Fe(II) spin crossover molecules (Fe(H2B(pz)?)?(bipy)) studied typically exist in at this paramagnetic low spin state at temperatures below 150 K, and ferromagnetic high spin state at temperatures above it. However, by mixing in highly polar molecules (p-benzoquinonemonime zwitterion) this transition temperature is ignored, and X-ray absorption spectroscopy reveals that the spin crossover molecules may exist in their low spin state at room temperature. Furthermore, this mixture of polar molecules and spin crossover is sensitive to X-rays, as exposing the mixture to them induces a transition from the paramagnetic low spin to the ferromagnetic high spin state. The process is reversible, as the molecules may be de-excited back to a low spin state by cooling them to 78 K. The study serves as a demonstration that the spin crossover transition may be tailored by mixing in different molecules, and that modifying these transitions points can result in new properties, such as the optical switching between magnetic states.

Download this event to my calendar