Neutron scattering measurements of spin fluctuations in hole-doped high-Tc copper oxides have revealed an unusual 'hour-glass' feature in the momentum-resolved magnetic spectrum. There is no widely accepted explanation for this feature. One possibility is that it derives from a pattern of alternating spin and charge stripes. Many copper oxides without stripe order, however, also exhibit an hour-glass spectrum. This paper reports the observation of an hour-glass magnetic spectrum in a hole-doped antiferromagnet from outside the family of superconducting copper oxides. The system has stripe correlations and is an insulator, which means its magnetic dynamics can conclusively be ascribed to stripes. The results provide compelling evidence that the hour-glass spectrum in the copper-oxide superconductors arises from fluctuating stripes.
- A. T. Boothroyd
- P. Babkevich
- P. G. Freeman
