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arXiv · 1601.01777

New phase transition in Na$_{2}$Ti$_{2}$As$_{2}$O revealed by Raman scattering

D. Chen·T. T. Zhang·Z. -D. Song·H. Li·W. -L. Zhang·T. Qian·J. -L. Luo·Y. -G. Shi·Z. Fang·P. Richard·H. Ding
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Abstract

We performed a Raman scattering study of Na$_2$Ti$_2$As$_2$O. We identified a symmetry breaking structural transition at around $T_s = 150$ K, which matches a large bump in the electrical resistivity. Several new peaks are detected below that transition. Combined with first-principles calculations, our polarization-dependent measurements suggest a charge instability driven lattice distortion along one of the Ti-O bonds that breaks the 4-fold symmetry and more than doubles the unit cell.

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D. Chen, T. T. Zhang, Z. -D. Song, H. Li, W. -L. Zhang, T. Qian, J. -L. Luo, Y. -G. Shi, Z. Fang, P. Richard, H. Ding. 2016-01-08. New phase transition in Na$_{2}$Ti$_{2}$As$_{2}$O revealed by Raman scattering. https://doi.org/10.1103/physrevb.93.140501

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