Frustrated magnets lie at a very promising interface between fundamental physics and materials science. With joint efforts between materials research and quantum chemistry, the combinatorial richness of the periodic table has often been harvested to generate new systems that are good candidates for several of the exotic properties observed in theoretical models.

An example of this is spin ice, a frustrated spin system that exhibits an extensive ground state degeneracy. This is approximately realized in a class of rare-earth compounds dubbed spin ice materials (e.g., Dy2Ti2O7 and Ho2Ti2O7), whose degrees of freedom at sufficiently low temperatures behave like microscopic magnets constrained to arrange themselves on a three-dimensional lattice in a way that closely resembles the structure of water ice (in its hexagonal phase). In collaboration with Prof. R. Moessner and Prof. S. L. Sondhi, we discovered that these compounds provide an instance of high-dimensional fractionalization. The spin degrees of freedom (magnetic dipoles) fractionalize into deconfined pairs of magnetic monopoles! [1].

Like in other examples of emergent phenomena, spin-ice materials provide a ground state (`vacuum') where exotic particles naturally arise, which are not usually observed in our universe. we are now studying the implications of this unusual behavior on the properties of spin ice materials.


  1. C. Castelnovo, R. Moessner, and S. L. Sondhi
    Magnetic Monopoles in Spin Ice
    arXiv:0710.5515v1 (2007) -- accepted for publication in Nature