The Spin-Wave Continuum of the S = 1/2 Linear Heisenberg Antiferromagnet

In the S=½ linear Heisenberg antiferromagnet (HB AF) [Formula can not be displayed here. Please see PDF] although investigated by various theoretical approaches -many important questions concerning the statics and the dynamics have remained open. Recent low-temperature neutron-scattering experiments on CuCl2 • 2N(C5H5) (CPC), which is a good realization of an S=½ HB AF chain, provided new important information on the dynamics of the system, such as lineshapes and the behaviour in a magnetic field /1/. The important quantity for direct comparison with experiments of this kind is the dynamic spin-correlation function in (q,ω) -space. It is the Fourier transform of \u3c Sz (l. t) Sz (l\u27, o) \u3e and for T = o it can be written as Gzz(q,ω) = Σλ Mλδ(ω + EO - Eλ), Mλ = 2π|\u3c o||Sz(q)||λ \u3e|