New states of matter may be produced if quantum effects and frustration conspire to prevent the ground state from achieving classical order. An example of a new quantum phase is the quantum spin liquid. Such spin liquids cannot be characterized by local order parameters; rather, they are distinctive by their possession of long range quantum entanglement. I will describe recent experimental progress in the quest to study quantum spin liquids in frustrated magnets. The kagome lattice, composed of corner-sharing triangles, is highly frustrated for antiferromagnetic spins. Materials based on the kagome lattice with spin-1/2 are ideal hosts for quantum spin liquid ground states. I will discuss our group’s work which includes single crystal growth, bulk characterization, and neutron scattering measurements of the S=1/2 kagome lattice material ZnCu3(OH)6Cl2 (also known as herbertsmithite). Our inelastic neutron scattering measurements of the spin correlations in a single crystal sample reveal that the excitations are fractionalized, a hallmark signature of spin liquid physics.
