Speaker
Description
Spin and charge stripe correlations and their dynamics have been well explored in the ordered state of La-based 214-nickelates for last 3 decades. Recently, we have also explored magnetic excitations in the ordered spin-stipes phases of hole-doped Pr-based nickelates Pr$_{2-x}$NiSrO$_{4+\delta}$ [1-3]. In this regards, what remains less explored is the fluctuating state of the spin stripes from which the long-range spin stripes develop on cooling. In this talk, we present our recent inelastic neutron scattering study of the low energy spin stripe fluctuations in Pr$_{2−x}$Sr$_{x}$NiO$_{4+\delta}$ with magnetic incommensurability ϵ= 0.33 above the spin stripe ordering temperature T$_{so}$ = 190 K [4]. The spin stripe fluctuations measured at the incommensurate wave vector show a non-dispersive character with no detectable anisotropy persisting up to a maximum energy 10 meV, and strongly suppressed already below the charge stripe ordering temperature T$_{co}$ = 255 K. Our results clearly indicate that the presence of static charge stripe order is essential for the spin stripe fluctuations in 214-type nickealtes.
References:
[1] A. Maity et al., Physical Review Letters 124, 147202 (2020).
[2] R. Dutta et al., Physical Review B 102, 165130 (2020).
[3] A. Maity et al., Physical Review B (Letter) 103, L100401 (2021).
[4] A. Maity et al., Physical Review B 106, 024414 (2022).
