First principles approach to strongly correlated materials

Simple item page
dc.contributor.advisorNevidomskyy, Andriy Hen_US
dc.creatorLoganathan, Vaideeshen_US
dc.date.accessioned2019-05-17T19:14:58Zen_US
dc.date.available2019-05-17T19:14:58Zen_US
dc.date.created2019-05en_US
dc.date.issued2019-04-19en_US
dc.date.submittedMay 2019en_US
dc.date.updated2019-05-17T19:14:58Zen_US
dc.description.abstractTheoretical studies stemming from first-principles calculations have played a crucial role in understanding the plethora of interesting properties exhibited by condensed matter systems. Density functional theory (DFT) based calculations have been widely used to study the electronic structure in various classes of materials. Strongly correlated materials possess unusual properties that challenge the assumptions of band-structure theory. Examples of such materials include Mott insulators, unconventional superconductors, heavy fermion materials, etc. Simplified models such as the Hubbard model have been developed to account for the correlated behavior of electrons. The DFT+U method as well as the many-body based Dynamical mean field theory (DMFT) methods provide a better description of strongly correlated materials. In this work, we study the aspects of the Mott transition in a transition metal compound, \ce{Sr_2Mn_2O_3As_2}. The study was experimentally motivated by measurements showing an interplay between the magnetic ordering and transport properties. We first obtain the electronic structure using DFT+U, showing signs of a Mott transtion. We identify the orbitals involved in magnetic ordering and the Mott transition. In order to model the system, we construct an effective tight-binding Hamiltonian involving two orbitals with the help of Wannier functions. We then solve the model using the approaches of DMFT as well as Variational cluster approximation (VCA). The results show the opening of the Mott gap in an orbital-selective fashion, i.e. the orbitals develop a gap at different critical values of the Hubbard interaction. In this dissertation, I first introduce the theoretical aspects of DFT, Wannier functions methodology, and DMFT. In the next chapter, I discuss the study on the material, \ce{Sr_2Mn_2O_3As_2}. I summarise the results obtained from DFT and DMFT to describe an orbital-selective Mott transition. In the last chapter, I include a few applications of DFT calculations to complement recent experimental findings in Yb-based heavy fermion compounds, and magnetic materials with competing interactions.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationLoganathan, Vaideesh. "First principles approach to strongly correlated materials." (2019) Diss., Rice University. <a href="https://hdl.handle.net/1911/106009">https://hdl.handle.net/1911/106009</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/106009en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectStrongly correlated materialsen_US
dc.subjectfirst-principles calculationsen_US
dc.titleFirst principles approach to strongly correlated materialsen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentPhysics and Astronomyen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.majorCondensed matter Physicsen_US
thesis.degree.nameDoctor of Philosophyen_US
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
LOGANATHAN-DOCUMENT-2019.pdf
Size:
13.23 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 2 of 2
No Thumbnail Available
Name:
PROQUEST_LICENSE.txt
Size:
5.85 KB
Format:
Plain Text
Description:
Download
No Thumbnail Available
Name:
LICENSE.txt
Size:
2.61 KB
Format:
Plain Text
Description:
Download
Collections
Rice University Theses and Dissertations