Presenter Name:              Rahul Mahavir Varma

Ph.D. Supervisor:            Prof. D. D. Sarma 

 Date & Time :                  18th July 2022 at 4:00 pm through Microsoft Teams 

 Title:                                 Electronic, magnetic and local structure of some selected strongly correlated systems

Meeting link: Click Here


According to independent electron band structure theories, 3d transition metal oxides (TMOs) are predicted to be metallic in nature due to their partially filled 3d valence bands. In contrast, most of them are insulators. Mott [1] and later Hubbard [2] introduced electron-electron interactions in order to explain such insulating behaviors. These systems are often known as Mott-Hubbard insulator (or Mott insulators). These systems have attracted a great deal of attention in the last several decades, not only due to the intriguing physics observed in these systems with variations in pressure, temperature, doping etc, but also due to their diverse application potentials. The discovery of high-temperature superconductivity (high ) in the copper based TMOs [3] regenerated the interest in these systems characterized by strong electron-electron interactions; such systems are generally called strongly correlated systems (SCS)  [4] to include materials that are not necessarily insulating, but whose properties are believed to be controlled by strong electron-electron interactions. These SCS, particularly those based on the 3d transition metal oxides, are of great importance and cover different phenomena such as metal-insulator transitions (MIT), high-TC superconductor, and colossal magnetoresistance. All such exciting properties shown by 3d TMOs are fundamentally due to the presence of partially filled 3d valence band and to understand such properties, one needs to investigate the electronic and crystal structures of these materials. In this thesis wok, we will be discussing the electronic, magnetic, and local geometric structures of some selected strongly correlated systems with interesting properties like MIT, and strong magneto-dielectric coupling with the help of different spectroscopic techniques such as high-energy x-ray photoemission, x-ray absorption, dielectric and magnetic measurements.



[1]      N. F. Mott, The Basis of the Electron Theory of Metals, with Special Reference to the Transition Metals, Proc. Phys. Soc. Sect. A 62, 416 (1949).

[2]      J. Hubbard, Electron Correlations in Narrow Energy Bands276, 238 (1963).

[3]      J. G. Bednorz and K. A. Müller, Perovskite‐Type Oxides—the New Approach to High‐Tc Superconductivity, Rev. Mod. Phys. 60, 585 (1988).

[4]      P. Fulde, Electron Correlations in Molecules and Solids (Springer Science & Business Media, 1995).