Mazumder Nilesh, Mandal Prasanta, Roy Rajarshi, Ghorai Uttam Kumar, Saha Subhajit, Chattopadhyay Kalyan Kumar
Physics Department, Jadavpur University, Kolkata 700032, India.
J Phys Condens Matter. 2017 Sep 20;29(37):375701. doi: 10.1088/1361-648X/aa7cb2. Epub 2017 Jun 30.
For weak or moderate doping, electrical measurement is not suitable for detecting changes in the charge localization inside a semiconductor. Here, to investigate the nature of charge-phonon coupling in the presence of gradually delocalized holes within a weak doping regime (~10 cm), we examine the temperature dependent Raman spectra (303-817 K) of prototype hole doped delafossite [Formula: see text] (x = 0/0.03, y = 0/0.01). For both [Formula: see text] and [Formula: see text] phonons, negative lineshape asymmetry and relative thermal hardening are distinctly observed upon [Formula: see text] and [Formula: see text] doping. Using Allen formalism, charge density of states at the Fermi level per spin and molecule, and charge delocalization associated to [Formula: see text] plane, are estimated to increase appreciably upon codoping compared to the [Formula: see text]-axis. We delineate the interdependence between charge-phonon coupling constant ([Formula: see text]) and anharmonic phonon lifetime ([Formula: see text]), and deduce that excitation of delocalized holes weakly coupled with phonons of larger [Formula: see text] is the governing feature of observed Fano asymmetry ([Formula: see text]) reversal.
对于弱或中度掺杂，电学测量不适用于检测半导体内部电荷局域化的变化。在此，为了研究在弱掺杂区域（~10¹⁹ cm⁻³）内空穴逐渐离域的情况下电荷 - 声子耦合的性质，我们研究了原型空穴掺杂铜铁矿[化学式：见原文]（x = 0/0.03，y = 0/0.01）的温度依赖拉曼光谱（303 - 817 K）。对于[化学式：见原文]和[化学式：见原文]声子，在[化学式：见原文]和[化学式：见原文]掺杂时明显观察到负的线形不对称和相对热硬化。使用艾伦形式理论，与[化学式：见原文]轴相比，共掺杂时每个自旋和分子在费米能级处的态电荷密度以及与[化学式：见原文]平面相关的电荷离域估计会显著增加。我们描绘了电荷 - 声子耦合常数（[化学式：见原文]）与非谐声子寿命（[化学式：见原文]）之间的相互依存关系，并推断与较大[化学式：见原文]的声子弱耦合的离域空穴的激发是观察到的法诺不对称（[化学式：见原文]）反转的主导特征。
