Anelastic relaxation and around the critical Sr content x = 0.02

TLDR: The phase diagram of La2-xSrxCuO4 at the boundary between the antiferromagnetic (AF) and the spin-glass phase (x = 0.02) could be more complicated than previously thought, with a transition to a quasi-long range ordered state at K, as indicated by neutron scattering data as mentioned in this paper.

Abstract: Anelastic relaxation and 139LaNQR relaxation rates in La2–xSrxCuO4 for Sr content around 2 and 3 percent are discussed in terms of spin and lattice excitations and of the related ordering processes. It is argued how the phase diagram of La2–xSrxCuO4 at the boundary between the antiferromagnetic (AF) and the spin-glass phase (x = 0.02) could be more complicate than previously thought, with a transition to a quasi-long range ordered state at K, as indicated by neutron scattering data. On the other hand, the 139LaNQR spectra are compatible with a transition to an AF phase around K, in agreement with the phase diagram commonly accepted in literature. In this case the peaks in NQR and anelastic relaxation rates around 150 K and 80 K respectively in La1.98Sr0.02CuO4, yield the first evidence of freezing process involving simultaneously lattice and spin excitations, possibly corresponding to motion of charged stripes.