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首页> 外文期刊>Physical review >Raman-active E_(2g) phonon in MgB_2: Electron-phonon interaction and anharmonicity
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Raman-active E_(2g) phonon in MgB_2: Electron-phonon interaction and anharmonicity

机译：MgB_2中的拉曼活性E_（2g）声子：电子-声子相互作用与非谐性

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摘要

Measurements of the Raman spectra in MgB_2 up to 750 K are presented. The width of the E_(2g) phonon line shows a pronounced maximum in the range of 350-400 K. In the same temperature range the frequency exhibits a sharp softening. The E_(2g) phonon line is superimposed on the electronic background, whose frequency also strongly depends on temperature. The phonon self-energies and spectra of electronic Raman scattering were calculated, taking into account a renormalization of ab initio electronic structure due to an electron-phonon scattering. We obtained a satisfactory description of the temperature dependence of the phonon linewidth and proved that it is mainly determined by nonadiabatic effects. Since the wave vector of the E_(2g) phonon is in the nonadiabatic range, the contribution of electrons to phonon damping dominates and determines its nonmonotonic behavior as a function of temperature. When the anharmonic contributions to the phonon frequency are taken into account, the total shift of the E_(2g) phonon energy agrees with the experiment at 300 K, but the estimates of the anharmonic terms in the high-temperature range need further clarification.
机译：提出了在MgB_2中达到750 K的拉曼光谱的测量。 E_（2g）声子线的宽度在350-400 K范围内显示出明显的最大值。在相同温度范围内，频率呈现出急剧的软化。 E_（2g）声子线叠加在电子背景上，其频率也强烈取决于温度。考虑到由于电子-声子散射引起的从头算起的电子结构的重新归一化，计算了声子自能和电子拉曼散射的光谱。我们获得了对声子线宽的温度依赖性的令人满意的描述，并证明了它主要由非绝热效应决定。由于E_（2g）声子的波矢在非绝热范围内，因此电子对声子阻尼的贡献起主导作用，并决定了其非单调行为随温度的变化。当考虑非声子对声子频率的贡献时，E_（2g）声子能量的总位移与在300 K时的实验一致，但是高温范围内非谐项的估计需要进一步阐明。

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  • 来源
    《Physical review》 |2017年第21期|214503.1-214503.7|共7页
  • 作者

    Yu. S. Ponosov; S. V. Streltsov;

  • 作者单位

    M.N. Mikheev Institute of Metal Physics UB RAS, 620108, S. Kovalevskaya Street 18, Ekaterinburg, Russia,Ural State Technical University, Mira Street 19, 620002 Ekaterinburg, Russia;

    M.N. Mikheev Institute of Metal Physics UB RAS, 620108, S. Kovalevskaya Street 18, Ekaterinburg, Russia,Ural State Technical University, Mira Street 19, 620002 Ekaterinburg, Russia;

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