Spin dynamics of Li Doped La[sub 2]CuO[sub 4]with a disordered ground state

Only 3% hole doping by Li is sufficient to suppress the long-range antiferromagnetic order in LazCu04. Spin dynamics in the disordered state was investigated by measuring the dynamic magnetic structure factor, S(q,w), as a function of temperature, using cold neutron spectroscopy, on La2Cuo.96Lio.0404a nd La∼Cuo.gLio.104s ingle crystals. The details of observed spin dynamics of the quantum disordered spin liquid were compared to the theoretical results of the nonlinear u model for a two dimensional Heisenberg antiferromagnet, which predicts a phase crossover upon cooling from a quantum critical regime of a quantum spin liquid to its quantum paramagnetic regime.