Structural transitions in the two-dimensional Jahn-Teller system K2CuxZn1-xF4 with the variation of x: experiments based on the Raman scattering of phonons
Structural transitions in the two-dimensional Jahn-Teller system K2CuxZn1-xF4 with the variation of x: experiments based on the Raman scattering of phonons
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二维 Jahn-Teller 系统 K2CuxZn1-xF4 中 x 变化的结构转变：基于声子拉曼散射的实验
DOI：
10.1088/0953-8984/3/35/022
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
I. Yamada
中科院分区：
文献类型：
--
作者：
Y. Fukada;M. Totani;I. Yamada
本文报道了不同Cu浓度x的K_2Cu_xZn_（1-x）F_4晶体中声子的拉曼散射的测量结果。随着x的减小，除了在x约0.4处的结构变化之外，在x约0.8处也确认了结构变化。比较1>或=x>0.8与0.8>x>0.4时的偏振光谱，作者发现在x约为0.8时，从D2 h到表观D4 h对称性的转变，这对应于CuF 6八面体的合作Jahn-Teller畸变的长程有序从三维到二维的变化。低于x约0.4，在每个c平面中的长程反铁磁畸变有序被破坏，如Natalum和Yamada（NY）在1985年报道的。在D2 h 18、D4 h 5和D4 h 17空间群假设下，对观测到的Stokes线（包括NY报道中x>0.8、0.8>x>0.4和0.4>x时遗漏的几条线）分别作了很好的解释。
Measurements are reported of the Raman scattering of phonons in many crystals of K2CuxZn1-xF4 with different Cu concentrations x. With decreasing x, a structural change is confirmed at x approximately 0.8 besides the one at x approximately 0.4. Comparing the observed polarized spectra for 1>or=x>0.8 with those for 0.8>x>0.4, the authors find a transition at x approximately 0.8 from the D2h to an apparent D4h symmetry, which corresponds to a change of the long-range order of the cooperative Jahn-Teller distortion of CuF6 octahedra from three-dimensional to two-dimensional. Below x approximately 0.4, the long-range antiferrodistortive order in each c plane is destroyed as reported by Natsume and Yamada (NY) in 1985. The observed Stokes line including several lines which were missed in the report by NY for x>0.8, 0.8>x>0.4 and 0.4>x are well explained on the assumption of the space groups of D2h18, D4h5 and D4h17, respectively.