Anomalous oxygen-isotope effect on the in-plane far-infrared conductivity of detwinned (YBa2Cu3O6.9)-O-16,18

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Authors	BERNHARD Christian HOLDEN Todd BORIS Alexandr KOVALEVA Natalia PIMENOV Alexei HUMLÍČEK Josef
Year of publication	2004
Type	Article in Periodical
Magazine / Source	Physical Review B
MU Faculty or unit	Faculty of Science
Citation
Field	Solid matter physics and magnetism
Keywords	CHARGE-DENSITY WAVES; OPTICAL CONDUCTIVITY; SUPERCONDUCTORS; TEMPERATURE; PSEUDOGAP; GAP; LA2-XSR(X)CUO4; ELLIPSOMETRY; SPECTROSCOPY; YBA2CU3O6+X
Description	We observe a large and anomalous oxygen isotope effect on the a-axis component of the far-infrared electronic response of detwinned (YBa2Cu3O6.9)-O-16,18. For O-18 a pronounced low-energy electronic mode (LEM) appears around 240 cm(-1). This a-axis LEM exhibits a clear aging effect, after 1 y it is shifted to 190 cm(-1). For O-16 we cannot resolve a corresponding a-axis LEM above 120 cm(-1). We interpret the LEM in terms of a collective electronic mode that is pinned by "isotopic defects," i.e., by the residual O-16 in the matrix of O-18.
Related projects:	Physical properties of new materials and layered structures