An End to the Drought of Quantum Spin Liquids

摘要

Electrons possess magnetic behavior through the quantum mechanical property of spin. The magnetic properties of materials then arise from the collective interaction of electrons on atoms within the crystal. Below a transition temperature, the electron spins of normal magnets "freeze" into an ordered array of magnetic dipoles. Whether the ordering is ferromagnetic (all the dipoles point in the same direction) or antiferromagnetic (the dipoles on adjacent sites point in opposite directions) is determined by the sign and strength of the interaction between the electrons. Early theoretical work has indicated a departure from these ordered states, suggesting that quantum mechanical fluctuations of the spin could be so strong that ordering would be suppressed and the spin ensemble would remain in a liquid-like state, even down to the lowest temperatures. Experimental evidence, which has until recently remained elusive, is emerging in favor of this long-predicted state of quantum matter.