The Magnetocaloric Effect
By Kemal Aziz
A theme prevalent throughout condensed matter physics is that microscopic fluctuations manifest as macroscopic behaviors. GdCo, for instance, exhibits the �magnetocaloric effect�, whereby the application of a magnetic field induces temperature changes in certain alloys, currently subject to ongoing research by General Electric. The Heisenberg Spin Hamiltonian is an operator used to calculate the total energy of a magnetic system, given matrices which represent �spin� magnetic moments of constituent, interacting atoms within a lattice. Geometric structures called space groups yield the periodic configuration of such a lattice in space, dependent on the material modelled. … I used existing space group parameters to understand how these temperature changes emerged from atomic-scale interactions.