Sr impurity effects on the magnetic correlations ofLa2−xSr

Systematic study of short-range antiferromagnetic order and the spin-glass state in lightly dopedLa2−xSrx

“…As pointed out by Gooding et al, 16 if the cluster spinglass state is realized in this system, each cluster consisting of an odd number of spins behaves like a single spin yielding a Curie type paramagnetic behavior. Hence, the number of effective Cu 2+ spins should be half of the total number of the clusters.…”

“…From a numerical calculation, Gooding et al 16 reported that L is given by L = Ax −η (A ∼ 0.49 and η ∼ 0.98) on the basis of the cluster spin-glass model with a random distribution of doped holes. In this model, the doped holes form the boundaries between the clusters.…”

“…From numerical simulations Gooding et al 16 explained the coexistence of the spin-glass state and quasi-static magnetic order as a cluster spin-glass state taking into account hole-localization around Sr ions. However, important unresolved problems exist for the physics in this intermediate doping region.…”

Unidirectional diagonal order and three-dimensional stacking of charge stripes in orthorhombicPr1.67Sr0.33NiO4andHücker1, Zimmermann2, Klingeler3 et al. 2006Phys. Rev. B

“…There are certainly alternative models for the lightlydoped cuprates that do not involve stripes; [27][28][29][30][31] however, there is also additional evidence for the cuprates suggesting a common coupling of charge and spin stripes to an orthorhombic lattice distortion. In La 2 CuO 4+␦ and La 1.88 Sr 0.12 CuO 4 , both systems with parallel stripes and LTO structure, it was observed that the direction of the spin stripes is not perfectly parallel to the Cu-O bonds, but slightly inclined towards the diagonally running octahedral tilt axis ͑ʈa͒, by an angle too large to be explained with the orthorhombic lattice distortion.…”

“…Therefore, one has to consider the possibility that here the incommensurate magnetism might emerge from ground states different from stripe order, such as helical spin structures or disorder-induced spin topologies. [26][27][28][29][30][31] To gain insight into the mechanisms of the charge-lattice coupling in the cuprates, we have carried out a study of the diagonal stripes in the isostructural nickelates. The particular question which motivated this work is: do lattice distortions in the nickelates, which are very similar to those in the cuprates, have an impact on the stripe orientation?…”