【摘要】 缺位尖晶石化合物AM₄X₈因其特殊的M₄四面体结构,体系呈现丰富的物理性质,如磁摆线态（cycloidal phase）、多铁性和skyrmion等,在信息存储、新型自旋电子器件及电阻存储器等领域有着重要的应用前景,从而引起了研究者们的广泛关注.本文通过偏振拉曼光谱和群论分析对GaV₄Se₈拉曼声子模进行了指认,包括3个A₁模,1个E模和2个T₂模,其中T1/2为JahnTeller （J-T）模.在变温拉曼光谱中,除T₁模外,所有声子模峰位和峰宽随温度的演化均符合非谐声子模型,且三声子相互作用占主导,尤其在J-T畸变和磁有序温度附近未发生异常演化.而T1/2模式表现为非温度依赖关系,其由较强的电声耦合导致,且与有序无序铁电相变特征相匹配.本文的研究揭示了GaV₄Se₈的拉曼活性声子模相关信息,为进一步研究J-T畸变与晶格动力学之间的关联提供了重要的实验参考.更多还原

【Abstract】 Lacunar spinel AM₄X₈ compounds,due to its unique M₄ tetrahedral structure,exhibits rich physical properties such as cycloidal state,multiferroic,skyrmion,etc,which have important application prospects in the fields of information storage,novel spintronic devices and resistance access memory,thus attracting extensive attention.In this paper,the Raman modes of GaV₄Se₈ single crystal are determined by polarization-resolved Raman spectroscopy and group theory analysis,including three A₁ modes,one E mode and two T₂ modes respectively,in which T₂¹ is a Jahn-Teller（J-T） mode.In the temperature-dependent Raman spectroscopy,except for the T₂¹ mode,the temperature evolution of peak position and FWHM for all phonon modes follows the anharmonic phonon model,with three-phonon interactions being the dominant factor,particularly without anomalous behavior near the J-T distortion and magnetic ordering temperature.On the other hand,the T₂¹ mode exhibits no temperature dependence,which may be attributed to its strong electron-phonon coupling and the order-disorder ferroelectric phase transition.This study reveals the Raman active phonon modes of GaV₄Se₈ and provides an important experimental reference for further study of the relationship between J-T distortion and lattice dynamics.更多还原