The low energy magnetic excitation spectrum of charge stripe ordered La 2−x Sr x NiO 4 , x = 0.4 and x = 0.45 samples, were studied by neutron scattering. Two excitation modes are observed in both materials, one from the ordered magnetic moments, and a second mode consistent with pseudo-one-dimensional antiferromagnetic excitations of the charge stripe electrons (q-1D). The dispersion of the q-1D excitation follows the same relation as in x = 1/3 composition, with even spectral weight in the two counterpropagating branches of the x = 0.4 sample, however in the x = 0.45 sample only one dispersion branch has any measurable spectral weight. The evolution of the q-1D excitations on doping to the checkerboard charge ordered phase is discussed. DOI: 10.1103/PhysRevB.95.064403 Variation between the hourglass shaped magnetic excitation spectrum of the cuprates compared to the magnetic excitations of charge stripe ordered La 2−x Sr x NiO 4+δ (LSNO) has called into question the relevance of the charge stripe picture for the cuprates [1][2][3][4][5]. Recently however, it has been shown that insulating charge stripe ordered La 5/3 Sr 1/3 CoO 4+δ (LSCoO) has an hourglass shaped magnetic excitation spectrum that can be explained within a similar linear spin wave model used to describe charge stripe ordered LSNO [6]. In the charge stripe model the reason behind the different excitation spectrums is in part due to disorder, but mainly due to the relative strength of the interstripe magnetic interaction across the charge stripe, relative to the the intrastripe interaction [6]. For a weak interstripe interaction an hourglass excitation is observed, whereas a strong interaction leads to the symmetric spin wave cones observed in LSNO [3,5]. The role of disorder in wiping out the mode that disperses away from the antiferromagnetic position has been established in a charge stripe ordered manganate, these modes are present at base temperature but they have no measurable intensity on warming to the magnetic ordering temperature [7]. In the case of La 2−x Sr x CoO 4+δ an alternative scenario for the hourglass excitation spectrum arising from disordered checkerboard charge-ordered state has been proposed [8]. With the recent direct evidence of charge stripe order in La 2−x Sr x CoO 4+δ , the origin of the magnetic hourglass excitation spectrum is in dispute in this material [9].In LSNO magnetic excitations of the charge stripe electrons are observed [10], whereas half-filled charge stripes in the cuprates appear to have no interunit cell spin interactions, and * pgfreeman@uclan.ac.uk the spin state of the charge stripes in LSCoO is effectively S = 0 [1,2]. In the case of the cuprates there is evidence for a Q = 0 intraunit cell magnetic order from certain experimental techniques [11], this is apparently affected by charge stripe order in La-based cuprates possibly indicating the involvement of spins of half-filled stripes [12]. It is necessary to understand the magnetic interactions of the charge stripe electrons in LSNO to throw ligh...