Proximity to a commensurate charge modulation in IrTe2-xSex (x=0 and 0.45) revealed by Raman spectroscopy
Proximity to a commensurate charge modulation in IrTe2-xSex (x=0 and 0.45) revealed by Raman spectroscopy
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DOI：
10.1088/1367-2630/16/9/093061
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发表时间：
2014-09-30
影响因子：
3.3
通讯作者：
Cheong, S-W
中科院分区：
文献类型：
--
作者：
Glamazda, A.;Choi, K-Y;Cheong, S-W
光学声子探测IrTe 2-xSex的结构相变在T-C类似于280 K的x = 0和T-C类似于491 K的x = 0.45，这是由Ir二聚与电荷调制。声子拉曼谱显示出相变温度和热滞的不连续变化。Se掺杂主要影响Te原子的离面运动的165 cm（-1）A（g）1模。这突出了层间Te-Te相互作用在诱导结构不稳定性中的作用。当温度低于T-C时，x = 0和x = 0.45的化合物在128 cm（-1）E-g 1面内模中通常有5个区带折叠峰，在165 cm（-1）A（g）1面内模中通常有6个区带折叠峰。这被视为单位晶胞的相应五倍和六倍的签名。我们的研究结果，一方面，是一致的1/5的电荷调制由以前的研究报告，另一方面，表明IrTe 2-xSex的基态在于接近1/6相称的电荷调制阶段。
Optical phonons are employed to probe a structural phase transition of IrTe2-xSex at T-C similar to 280 K for x = 0 and T-C similar to 491 K for x = 0.45, which is dictated by Ir dimerization with charge modulations. Phonon Raman spectra show a discontinuous change at T-C and thermal hysteresis. A 165 cm(-1) A(g) 1 mode involving out-of-plane motions of Te atoms is mostly affected by Se doping. This highlights the role of interlayer Te-Te interactions in inducing the structural instability. For temperatures below T-C both x = 0 and x = 0.45 compounds exhibit commonly five zone-folded peaks for the 128 cm(-1) E-g 1 in-plane mode and six zone-folded peaks for the 165 cm(-1) A(g) 1 mode. This is taken as a signature of a respective quintupling and sextupling of the unit cell. Our results, on the one hand, are consistent with a 1/5 charge modulation reported by previous studies and, on the other hand, indicate that the ground state of IrTe2-xSex lies in proximity to a 1/6 commensurate charge modulation phase.