Spin dynamics in a hole-doped S=1/2 Heisenberg antiferromagnet with a disordered ground state

TL;DR

This study investigates the spin dynamics in a heavily hole-doped, disordered S=1/2 Heisenberg antiferromagnet, revealing relaxational behavior and a finite energy scale at low temperatures, with implications for understanding the pseudogap in cuprates.

Contribution

It provides experimental insights into the spin dynamics of a disordered, hole-doped antiferromagnet, confirming theoretical predictions and linking to pseudogap phenomena.

Findings

Spin dynamics sharply peak at (pi,pi)

Dynamics are relaxational in nature

Energy scale saturates at low temperatures

Abstract

Only 3% hole doping by Li is sufficient to suppress the long-range antiferromagnetic order in La2CuO4. Spin dynamics in such a disordered state was investigated with measurements of the dynamic magnetic structure factor S(omega,q), using cold neutron spectroscopy, for La2(Cu0.94Li0.06)O4. The S(omega,q) is found to sharply peak at (pi,pi), and its dynamics to be relaxational. Confirming theoretical expectation for the quantum disordered 2D S=1/2 Heisenberg antiferromagnet, the energy scale saturates at a finite value at low temperatures. Possible connection to the ``pseudo spin gap'' phenomenon observed in the NMR/NQR studies on underdoped cuprates is discussed.