Mengfan Guo

Polar materials

I study polar materials for energy and information applications. The focus is on the static and dynamic arrangements of electrical dipoles, which lead to the emergence of interesting dielectric, thermal, magnetic, and optical properties.

Toroidal topologies

In ferroelectric materials, strong polarity is normally accompanied by strong dielectric anisotropy, facilitating rigid dipole alignment with crystallographic axes. By contrast, ferroelectric polymers display toroidal topology when the polar energy landscape becomes mechanically degenerate due to biaxial strain and chemically degenerate due to conformational disorder. In materials that consequently exhibit polar frustration, I study the emergent dielectric, piezoelectric, and optical properties.

Electrocaloric effects

Thermal changes that are reversibly driven by electric fields arise in polar materials as a result of modifications to the internal order. These electrocaloric effects can be pronounced if polarisation disorder is effectively harnessed, for example by coupling to disorder associated with structural degrees of freedom. I study electrocaloric materials that hold promise for efficient and eco-friendly heat pumps.