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arXiv · 1504.01779

Oxygen Isotope Effects on Lattice Properties of La_{2-x}Ba_xCuO_4 (x = 1/8)

Z. Guguchia·D. Sheptyakov·E. Pomjakushina·K. Conder·R. Khasanov·A. Shengelaya·A. Simon·A. Bussmann-Holder·H. Keller
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Abstract

A novel negative oxygen-isotope (16O/18O) effect (OIE) on the low-temperature tetragonal phase transition temperature T_{LTT} was observed in La_{2-x}Ba_xCuO_4 (x = 1/8) using high-resolution neutron powder diffraction. The corresponding OIE exponent alpha(T_{LTT}) = - 0.36(5) has the same sign as alpha(T_{so}) = -0.57(6) found for the spin-stripe order temperature T_so. The fact that the LTT transition is accompanied by charge ordering (CO) implies the presence of an OIE also for the CO temperature T_co. Furthermore, a temperature dependent shortening of the c-axis with the heavier isotope is observed. These results combined with model calculations demonstrate that anharmonic electron-lattice interactions are essential for all transitions observed in the stripe phase of cuprates.

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Z. Guguchia, D. Sheptyakov, E. Pomjakushina, K. Conder, R. Khasanov, A. Shengelaya, A. Simon, A. Bussmann-Holder, H. Keller. 2015-04-07. Oxygen Isotope Effects on Lattice Properties of La_{2-x}Ba_xCuO_4 (x = 1/8). https://doi.org/10.1103/physrevb.92.024508

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