New phase transition in Na2 Ti2 As2 O revealed by Raman scattering.

Authors :: Chen, D.
Zhang, T.-T.
Song, Z.-D.
Li, H.
Zhang, W.-L.
Qian, T.
Luo, J.-L.
Shi, Y.-G.
Fang, Z.
Richard, P.
Ding, H.
Source :: Physical Review B. Apr2016, Vol. 93 Issue 14, p1-1. 1p.
Publication Year :: 2016
Abstract: We performed a Raman scattering study of Na2 Ti2 As2 O. We identified a symmetry breaking structural transition at around Ts = 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 fourfold symmetry and more than doubles the unit cell. [ABSTRACT FROM AUTHOR]