Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in La2−xSrxCuO4. Bendele, M., von Rohr, F., Guguchia, Z., Pomjakushina, E., Conder, K., Bianconi, A., Simon, A., Bussmann-Holder, A., & Keller, H. Physical Review B, 95(1):014514+, 2017.
Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in La2−xSrxCuO4 [link]Paper  doi  abstract   bibtex   
The oxygen isotope (\${\textasciicircum}16{\textbackslash}mathrmO\$/\${\textasciicircum}18{\textbackslash}mathrmO\$) effect (OIE) on the pseudogap (charge-stripe ordering) temperature \$T{\textasciicircum}*\$ is investigated for the cuprate superconductor \${\textbackslash}mathrmLa_2{\textbackslash}ensuremath-x{\textbackslash}mathrmSr_x{\textbackslash}mathrmCuO_4\$ 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{\textasciicircum}*\$ is observed. The OIE exponent \${\textbackslash}ensuremath{\textbackslash}alpha_T{\textasciicircum}*\$ systematically decreases from \${\textbackslash}ensuremath{\textbackslash}alpha_T{\textasciicircum}*={\textbackslash}ensuremath-0.6(1.3)\$ for \$x=0.15\$ to \${\textbackslash}ensuremath{\textbackslash}alpha_T{\textasciicircum}*={\textbackslash}ensuremath-4.4(1.1)\$ for \$x=0.06\$, corresponding to increasing \$T{\textasciicircum}*\$ and decreasing superconducting transition temperature \$T_c\$. Both \$T{\textasciicircum}*({\textasciicircum}16{\textbackslash}mathrmO)\$ and \$T{\textasciicircum}*({\textasciicircum}18{\textbackslash}mathrmO)\$ exhibit a linear doping dependence with different slopes and critical end points [where \$T{\textasciicircum}*({\textasciicircum}16{\textbackslash}mathrmO)\$ and \$T{\textasciicircum}*({\textasciicircum}18{\textbackslash}mathrmO)\$ fall to zero] at \$x_c({\textasciicircum}16{\textbackslash}mathrmO)=0.201(4)\$ and \$x_c({\textasciicircum}18{\textbackslash}mathrmO)=0.182(3)\$, indicating a large positive OIE of \$x_c\$ with an exponent of \${\textbackslash}ensuremath{\textbackslash}alpha_x_c=0.84(22)\$. The remarkably large and strongly doping dependent OIE on \$T{\textasciicircum}*\$ 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.
@article{bendele_evidence_2017,
	title = {Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in {La}2−{xSrxCuO}4},
	volume = {95},
	issn = {2469-9950},
	url = {http://dx.doi.org/10.1103/physrevb.95.014514},
	doi = {10.1103/physrevb.95.014514},
	abstract = {The oxygen isotope (\${\textasciicircum}16{\textbackslash}mathrmO\$/\${\textasciicircum}18{\textbackslash}mathrmO\$) effect (OIE) on the pseudogap (charge-stripe ordering) temperature \$T{\textasciicircum}*\$ is investigated for the cuprate superconductor \${\textbackslash}mathrmLa\_2{\textbackslash}ensuremath-x{\textbackslash}mathrmSr\_x{\textbackslash}mathrmCuO\_4\$ 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{\textasciicircum}*\$ is observed. The OIE exponent \${\textbackslash}ensuremath{\textbackslash}alpha\_T{\textasciicircum}*\$ systematically decreases from \${\textbackslash}ensuremath{\textbackslash}alpha\_T{\textasciicircum}*={\textbackslash}ensuremath-0.6(1.3)\$ for \$x=0.15\$ to \${\textbackslash}ensuremath{\textbackslash}alpha\_T{\textasciicircum}*={\textbackslash}ensuremath-4.4(1.1)\$ for \$x=0.06\$, corresponding to increasing \$T{\textasciicircum}*\$ and decreasing superconducting transition temperature \$T\_c\$. Both \$T{\textasciicircum}*({\textasciicircum}16{\textbackslash}mathrmO)\$ and \$T{\textasciicircum}*({\textasciicircum}18{\textbackslash}mathrmO)\$ exhibit a linear doping dependence with different slopes and critical end points [where \$T{\textasciicircum}*({\textasciicircum}16{\textbackslash}mathrmO)\$ and \$T{\textasciicircum}*({\textasciicircum}18{\textbackslash}mathrmO)\$ fall to zero] at \$x\_c({\textasciicircum}16{\textbackslash}mathrmO)=0.201(4)\$ and \$x\_c({\textasciicircum}18{\textbackslash}mathrmO)=0.182(3)\$, indicating a large positive OIE of \$x\_c\$ with an exponent of \${\textbackslash}ensuremath{\textbackslash}alpha\_x\_c=0.84(22)\$. The remarkably large and strongly doping dependent OIE on \$T{\textasciicircum}*\$ 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.},
	number = {1},
	journal = {Physical Review B},
	author = {Bendele, M. and von Rohr, F. and Guguchia, Z. and Pomjakushina, E. and Conder, K. and Bianconi, A. and Simon, A. and Bussmann-Holder, A. and Keller, H.},
	year = {2017},
	pages = {014514+}
}

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