Two Ising-like magnetic excitations in a single-layer cuprate superconductor

Abstract

There exists increasing evidence that the phase diagram of the high-transition temperature (Tc) cuprate superconductors is controlled by a quantum critical point. One distinct theoretical proposal is that, with decreasing hole-carrier concentration, a transition occurs to an ordered state with two circulating orbital currents per CuO2 square. Below the 'pseudogap' temperature T* (T* > Tc), the theory predicts a discrete order parameter and two weakly-dispersive magnetic excitations in structurally simple compounds that should be measurable by neutron scattering. Indeed, novel magnetic order and one such excitation were recently observed. Here, we demonstrate for tetragonal HgBa2CuO4+d the existence of a second excitation with local character, consistent with the theory. The excitations mix with conventional antiferromagnetic fluctuations, which points toward a unifying picture of magnetism in the cuprates that will likely require a multi-band description.

Including supplementary information

References in corpus (12)

• Magnetic order in the pseudogap phase of high-$T_C$ superconductors
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• Spin dynamics in the pseudogap state of a high-temperature superconductor
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• 2D orbital-like magnetic order in $\mathrm{L}{\mathrm{a}}_{2-\mathrm{x}}\mathrm{S}{\mathrm{r}}_{\mathrm{x}}\mathrm{Cu}{\mathrm{O}}_4$
• Evidence for competing magnetic instabilities in underdoped $\mathrm{YB}{\mathrm{a}}_2\mathrm{C}{\mathrm{u}}_3{\mathrm{O}}_{6+\mathrm{x}}$
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Cited by in corpus (4)

• Macroscopic phase segregation in superconducting K0.73Fe1.67Se2 as seen by muon spin rotation and infrared spectroscopy
• Staggered Flux State in Two-Dimensional Hubbard Models
• Q=0 collective modes originating from the low-lying Hg-O band in the superconducting HgBa2CuO4+δ
• Discerning electronic fingerprints of nodal and antinodal nestings and their phase coherences in doped cuprate superconductors