Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in La2−x Srx CuO4

DOI: 10.1103/PhysRevB.95.014514

Authors: M. Bendele (Physik-Institut der Universitat Zurich) , F. Von Rohr (Physik-Institut der Universitat Zurich) , Z. Guguchia (Paul Scherrer Institute) , E. Pomjakushina (Paul Scherrer Institute) , K. Conder (Paul Scherrer Institute) , A. Bianconi (Rome International Center for Materials Science Superstripes (RICMASS); National Research Nuclear University) , A. Simon (6Max-Planck Institute for Solid State Research) , A. Bussmann-Holder (Max-Planck Institute for Solid State Research) , H. Keller (Physik-Institut der Universitat Zurich)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 95

State: Published (Approved)
Published: January 2017
Diamond Proposal Number(s): 9960

Abstract: The oxygen isotope (16O/18O) effect (OIE) on the pseudogap (charge-stripe ordering) temperature T∗ is investigated for the cuprate superconductor La2−xSrxCuO4 as a function of doping x by means of x-ray absorption near edge structure studies. A strong x dependent and sign reversed OIE on T∗ is observed. The OIE exponent αT∗ systematically decreases from αT∗=−0.6(1.3) for x=0.15 to αT∗=−4.4(1.1) for x=0.06, corresponding to increasing T∗ and decreasing superconducting transition temperature Tc. Both T∗(16O) and T∗(18O) exhibit a linear doping dependence with different slopes and critical end points [where T∗(16O) and T∗(18O) fall to zero] at xc(16O)=0.201(4) and xc(18O)=0.182(3), indicating a large positive OIE of xc with an exponent of αxc=0.84(22). The remarkably large and strongly doping dependent OIE on T∗ signals a substantial involvement of the lattice in the formation of the pseudogap, consistent with a polaronic approach to cuprate superconductivity and the vibronic character of its ground state.

Journal Keywords: Dopants; Electronic structure; Isotope effect; Phase diagrams; Pseudogap; Superconducting gap; Cuprates

Subject Areas: Physics, Materials


Instruments: B18-Core EXAFS

Added On: 18/05/2017 12:04

Discipline Tags:

Superconductors Quantum Materials Physics Hard condensed matter - structures Materials Science

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) X-ray Absorption Near Edge Structure (XANES)