Condensed Matter Experiment

My research focuses on emergent phenomena in correlated electronic materials.  We start with the synthesis, through crystal growth, of strongly interacting magnetic materials.  Our main tool of discovery is then neutron scattering, which allows us to understand the magnetic correlations in these new materials.   A particularly exciting goal of this research is to realize what is known as the Quantum Spin Liquid state, where magnetic moments dance together in an entangled, correlated, but ultimately disordered and dynamic way.

The theme of emergence can be fruitfully explored within the realm of periodic crystal lattices. Magnetic crystals with quantum degrees of freedom offer enormous diversity of emergent phenomena arising from simple near-neighbor interactions in a vast group of magnetic ions (~10²³ of them!). Dynamics ranging from “classical” spin waves that propagate a spin flip through an array of aligned moments, to emergent photon-like excitations that mimic electrodynamics, can be created, probed, and understood in this environment.

We use neutron scattering to directly probe the static and dynamic correlations in such materials. Neutron scattering has the advantage of providing directional and energy-resolved information (in 4-dimensional datasets), which can be successfully and simply compared with theory. Through collaborations with solid state chemists and condensed matter theorists, we strive to push the boundaries of magnetic solids towards strongly quantum entangled states.

Selected Publications

• Order by Disorder Spin Wave Gap in the XY Pyrochlore Magnet Er2Ti2O7. Phys. Rev. Lett. 112, 057201 (2014).
• Lightly stuffed pyrochlore structure of single-crystalline Yb2Ti2O7 grown by the optical floating zone technique. Phys. Rev. B 86, 174424 (2012).
• Order by Quantum Disorder in Er₂Ti₂O₇. Phys. Rev. Lett. 109, 167201 (2012).
• Quantum Excitations in Quantum Spin Ice. Phys. Rev. X 1, 021002 (2011).
• Neutron Laue Diffraction Study on the Magnetic Phase Diagram of Multiferroic MnWO4 under Pulsed High Magnetic Fields. Phys. Rev. Lett., 106, 237202 (2011).