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Marianne Haroche

 Marianne Haroche

Marianne Haroche

Member of Gonville and Caius College
PhD student in Dr Castelnovo's group

Office: 510 Mott Bld
Phone: +44(0)1223 3 37340
Email: mh732 @

TCM Group, Cavendish Laboratory
19 JJ Thomson Avenue,
Cambridge, CB3 0HE UK.


I am interested in frustrated magnetic systems, whose special feature is to present emergent point-like excitations with long-range interactions. In particular, in spin ice materials, these excitations take the form of magnetic monopoles interacting via Coulomb interaction energy. My aim is currently to investigate the dynamical behaviour of these monopoles and its interplay with the spin background using out-of-equilibrium physics of reaction-diffusion processes.

In Plain English

Frustrated systems are materials in which, due to geometric constraints, all the competing interactions cannot be minimized simultaneously. As a consequence, the ground state is macroscopically degenerated: a huge number of equivalent sates share the same energy, and the system remains disordered even at very low temperatures. Water ice was the first frustrated system to be identified. Later on a magnetic analogue of ice, for this reason named spin ice, was discovered. This class of materials is characterized by the presence of magnetic moments residing on the sites of a pyrochlore lattice, the same as the one occupied by the oxide ions of water ice, and therefore present the same geometric frustration. In spin ice, the elementary excitations above the degenerated ground state come from the appearance of defects in the spin configuration. They take the form of free magnetic charges, the emergent magnetic monopoles. At low temperature, instead of working directly with spins, we can thus use an effective description of the system in terms of a gas of Coulomb interacting charges, whose dynamics is constrained by the spin configuration.