IJSRST184917 | Received : 15 Dec 2017 | Accepted : 31 Dec 2017 | November-December-2017 [(3)8: 1502-1508 ] © 2017 IJSRST | Volume 3 | Issue 8 | Print ISSN : 2395-6011 | Online ISSN : 2395-602X Themed Section: Science and Technology 1502 Raman Scattering in High Temperature Superconductors A P Singh 1* , Yogendra Kumar 2 , Sanjay Kumar 3 1 Physics Department, M. M. College Modinagar, Uttar Pradesh, India 2 Physics Department, V S P Government Degree College Kairana, Uttar Pradesh, India 3 Department of Physics, J.V. Jain College, Saharanpur, Uttar Pradesh, India ABSTRACT The detailed study of Raman Scattering in high temperature Superconductors (HTS) via using the quantum dynamical approach of double time temperature dependent phonon-Green’s functions. The theory of first- order Raman scattering, second-order Raman scattering, third-order Raman scattering and electron-phonon contribution Raman scattering is investigated for high temperature superconductors. Raman tensor, intensity of Raman lines and differential cross-sections of various orders of scattering have been investigated. It has been developed using almost complete Hamiltonian which consists of the contributions due to the unperturbed phonons and electrons, anharmonic phonon fields, localized phonon fields and that of electron-phonon interactions. The temperature and defect dependencies are discussed in detail along with the nature of continues and line spectra. The phonon Raman scattering spectral density function has been obtained and analyzed for high temperature superconductors. Keywords: High Temperature Superconductors, Raman Scattering, Electron-Phonon Interaction, Green's Function Technique, Hamiltonian I. INTRODUCTION Raman scattering is an excellent technique to characterize and to investigate basic physical properties of high temperature superconductors. However, many properties have not yet been understood in the field of high temperature superconductors The Raman scattering has played an important role to investigate the properties of the gap function. A wide range of experimental techniques can be employed to investigate this type of properties [1, 2]. The multi-phonon interactions triggered for the calculation of thermal, optical and elastic properties of crystals. Mostly purposed theories are based on the harmonic approximation [3]. We should not expect the harmonic theory to be correct, even at the lowest temperatures. The influence of anharmonicities does not vanish even at the absolute temperature [4]. In addition to anharmonicity the presence of impurity dramatically modifies the phonon spectrum of the crystal and, hence, substantial changes occur in energy dependent properties of the crystal [5]. The interactions such as: phonon interactions in the anharmonic crystal fields, phonon interactions in the localized fields of crystal impurity, anharmonic phonon interactions with localized phonons and electron-phonon interactions. These interactions give rise to anharmonic mode, impurity modes and impurity-anharmonicity interference modes. The involvement of anharmonic and impurity effects can cause considerable alternation in the phonon Raman intensity. In this work, we shall amply the powerful Green’s function technique to investigate the Raman intensity in high temperature superconductors. This thermodynamic Green’s function technique has become an invaluable tool in the study of complicated systems of interacting particles [6-8]. In case of Raman line both the Raman shifts and line widths, and also the scattered intensities vary with temperature.