Unusual Magnetic Order in the Pseudogap Region of the Superconductor HgBa2CuO4+d
The pseudogap region of the phase diagram is an important unsolved puzzle in the field of high-transition-temperature (high-T{sub c}) superconductivity, characterized by anomalous physical properties. There are open questions about the number of distinct phases and the possible presence of a quantum-critical point underneath the superconducting dome. The picture has remained unclear because there has not been conclusive evidence for a new type of order. Neutron scattering measurements for YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} (YBCO) resulted in contradictory claims of no and weak magnetic order, and the interpretation of muon spin relaxation measurements on YBCO and of circularly polarized photoemission experiments on Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} has been controversial. Here we use polarized neutron diffraction to demonstrate for the model superconductor HgBa{sub 2}CuO{sub 4+{delta}} (Hg1201) that the characteristic temperature T* marks the onset of an unusual magnetic order. Together with recent results for YBCO, this observation constitutes a demonstration of the universal existence of such a state. The findings appear to rule out theories that regard T* as a crossover temperature rather than a phase transition temperature. Instead, they are consistent with a variant of previously proposed charge-current-loop order that involves apical oxygen orbitals, and with the notion that many of the unusual properties arise from the presence of a quantum-critical point.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1035128
- Report Number(s):
- SLAC-PUB-13413; TRN: US1200920
- Journal Information:
- Nature, Vol. 455, Issue 7211; ISSN 0028--0836
- Country of Publication:
- United States
- Language:
- English
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