Speaker
Description
Magnetic excitations in stripe-phases of $La-$based hole-doped $214-$ nickelates, especially in the $Sr-$doped ones, have been vigorously explored using inelastic neutron scattering (INS) studies. In $Sr-$ doped samples, the spin stripe correlation is relatively short-ranged due to unavoidable disorder introduced by the randomly distributed dopant. However, often the results have been compared with the linear spin wave (LSW) theory-based calculations, which assume long-range spin-stripe ordering.
In this talk, we will present the effect of long-range spin stripe ordering on the magnetic excitations of an $O-$ doped $214-$ nickelate Pr$_2$NiO$_{4+δ}$ ($\delta \sim 0.24$), where we find the spin stripe correlation is quite long-ranged $(\sim 50$ Å) compared to the $Sr-$ doped Pr$_{2-x}$SrNiO$_4$ ($\sim 20$ Å). For our investigation, we have performed the INS measurements using the thermal triple-axis spectrometer PUMA at MLZ, IN8 at ILL, and time-of-fight spectrometer MAPS at ISIS. Our investigation presents an intriguing observation of multiple equivalent weak modes in the spin wave dispersion of $O-$ doped Pr$_{2-x}$SrNiO$_4$ [1], which we have interpreted from the internal periodicity of the long-range ordered discommensurated spin stripes.
Reference: [1] A. Maity, R. Dutta, A. Marsicano, A Piovano, J. Ross Stewart and W. Paulus Phys. Rev. B 103, L100401 (2021).
