Hour-glass magnetic spectrum in a stripe-less insulating transition metal oxide

Abstract

An hour-glass shaped magnetic excitation spectrum appears to be an universal characteristic of the high-temperature superconducting cuprates. Fluctuating charge stripes or alternative band structure approaches are able to explain the origin of these spectra. Recently, an hour- glass spectrum has been observed in an insulating cobaltate, thus, favouring the charge stripe scenario. Here we show that neither charge stripes nor band structure effects are responsible for the hour-glass dispersion in a cobaltate within the checkerboard charge ordered regime of La2-xSrxCoO4. The search for charge stripe ordering reflections yields no evidence for charge stripes in La1.6Sr0.4CoO4 which is supported by our phonon studies. With the observation of an hour-glass-shaped excitation spectrum in this stripe-less insulating cobaltate, we provide experimental evidence that the hour-glass spectrum is neither necessarily connected to charge stripes nor to band structure effects, but instead, probably intimately coupled to frustration and arising chiral or non-collinear magnetic correlations.

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Cited by in corpus (10)

• Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides La${}_{2-x}$Sr${}_x$CoO${}_4$
• Direct evidence for charge stripes in a layered cobalt oxide
• Incommensurate spin correlations in highly oxidized cobaltates La${}_{2-x}$Sr${}_x$CoO${}_4$
• Stripe disorder and dynamics in the hole-doped antiferromagnetic insulator La5/3Sr1/3CoO4
• Magnetic phase diagram of La${}_{2-x}$Sr${}_x$CoO${}_4$ revised using muon-spin relaxation
• Magnetic excitations of the charge stripe electrons below half doping in La(2-x)Sr(x)NiO4, x = 0.45 and x = 0.4
• Stability of charge-stripe ordered La2-xSrxNiO4+delta at one third doping
• Opening a nodal gap by fluctuating spin-density-wave in lightly doped La${}_{2-x}$Sr${}_x$CuO${}_4$
• Evolution of valence-specific spin states and local distortions in La${}_{2-x}$Sr${}_x$CoO${}_4$
• Charge disproportionation and nano phase separation in $R$SrNiO${}_4$