Spontaneous breaking of time-reversal symmetry in the pseudogap state of a high-T{sub c} superconductor.

Journal Article · Thu Apr 11 04:00:00 EDT 2002 · Nature

DOI:https://doi.org/10.1038/416610a· OSTI ID:949632

Kaminski, A; Rosenkranz, S; Fretwell, H M; Campuzano, J C; Li, Z; Raffy, H; Cullen, W G; You, H; Olson, C G; Varma, C M; Hochst, H

A change in 'symmetry' is often observed when matter undergoes a phase transition--the symmetry is said to be spontaneously broken. The transition made by underdoped high-transition-temperature (high-{Tc}) superconductors is unusual, in that it is not a mean-field transition as seen in other superconductors. Rather, there is a region in the phase diagram above the superconducting transition temperature {Tc} (where phase coherence and superconductivity begin) but below a characteristic temperature T* where a 'pseudogap' appears in the spectrum of electronic excitations. It is therefore important to establish if T* is just a cross-over temperature arising from fluctuations in the order parameter that will establish superconductivity at Tc or if it marks a phase transition where symmetry is spontaneously broken. Here we report that, for a material in the pseudogap state, left-circularly polarized photons give a different photocurrent from right-circularly polarized photons. This shows that time-reversal symmetry is spontaneously broken below T*, which therefore corresponds to a phase transition.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; NSF; FOR
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 949632
• Report Number(s): ANL/MSD/JA-42729
• Journal Information: Nature, Journal Name: Nature Journal Issue: 6881 ; Apr. 11, 2002 Vol. 416
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
FLUCTUATIONS
ORDER PARAMETERS
PHASE DIAGRAMS
PHOTOCURRENTS
PHOTONS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
SYMMETRY
TRANSITION TEMPERATURE