Spin Dynamics of Half-Doped La3/2Sr1/2NiO4

Abstract

We report polarized- and unpolarized- neutron inelastic scattering measurements of the magnetic excitation spectrum in the spin-charge ordered phase of La3/2Sr1/2NiO4. Up to energies of ~30 meV we observe broad magnetic modes characteristic of a near checkerboard ordering. A linear spin-wave model for an ideal checkerboard ordering with a single antiferromagnetic exchange interaction J' = 5.8 +/- 0.5 meV between next-nearest-neighbour spins on Ni2+ sites, together with a small XY-like single-ion anisotropy, provides a reasonable description of the measured dispersion. Above 30 meV the excitations are not fully consistent with the linear spin-wave model, with modes near the two-dimensional reciprocal space wavevector (0.5,0.5) having an anomalously large intensity. Furthermore, two additional dispersive modes not predicted by spin wave theory were observed, both of which are probably magnetic. One disperses away from (0.5,0.5) in the energy range between 50-56 meV, and the other appears around (h,k) type positions (h,k = integer) in the energy range 31-39 meV. We propose a model in which these anomalous features are explained by the existence of discommensurations in the checkerboard ordering. At low energies there is additional diffuse scattering centred on the magnetic ordering wavevector. We associate this diffuse scattering with dynamic antiferromagnetic correlations between spins attached to the doped holes.

10 pages, 8 figures

References in corpus (8)

• A `checkerboard' electronic crystal state in lightly hole-doped Ca_{2-x}Na_{x}CuO_{2}Cl_{2}
• Spin dynamics in stripe-ordered La5/3Sr1/3NiO4
• Orbital Ordering, New Phases, and Stripe Formation in Doped Layered Nickelates
• Spin correlations among the charge carriers in an ordered stripe phase
• Spin reorientation transition in the incommensurate stripe-ordered phase of La3/2Sr1/2NiO4
• Magnetic Order and Dynamics in Stripe-Ordered La2-xSrxNiO4
• Magnetic excitations in La${}_{1.5}$Sr${}_{0.5}$CoO${}_4$
• Spin excitations in stripe-ordered La2-xSrxNiO4 (x=0.275 and 1/3)

Cited by in corpus (13)

• Electronic and magnetic excitations in La${}_3$Ni${}_2$O${}_7$
• Normal and superconducting properties of La${}_3$Ni${}_2$O${}_7$
• Neutron scattering studies on stripe phases in non-cuprate materials
• Doping Dependence of Collective Spin and Orbital Excitations in Spin 1 Quantum Antiferromagnet La${}_{2-x}$Sr${}_x$NiO${}_4$ Observed by X-rays
• Magnetic order and dynamics of the charge-ordered antiferromagnet La1.5Sr0.5CoO4
• Energy-dependent crossover from anisotropic to isotropic magnetic dispersion in lightly-doped La1.96Sr0.04CuO4
• Low energy, quasi-one-dimensional, spin dynamics in charge-ordered La(2-x)Sr(x)NiO(4)
• Spin-wave dispersion in half-doped LaSrNiO
• Magnetic excitations of the charge stripe electrons below half doping in La(2-x)Sr(x)NiO4, x = 0.45 and x = 0.4
• Spin excitations coupled with lattice and charge dynamics in La${}_{2-x}$Sr${}_x$CuO${}_4$
• Stability of charge-stripe ordered La2-xSrxNiO4+delta at one third doping
• Magnetic excitations in Nd${}_{n+1}$Ni${}_n$O${}_{3n+1}$ Ruddlesden-Popper nickelates observed via resonant inelastic x-ray scattering
• Development of the Magnetic Excitations of Charge-Stripe Ordered La(2-x)Sr(x)NiO(4) on Doping Towards Checkerboard Charge Order