Mentor: Betül Pamuk

Mentor's Responsibility for PARADIM:  Staff Scientist

REU intern:  Chase Hanson

Betül Pamuk obtained her B.S. (2008) degree from Bilkent University, Turkey; and M.A. (2011) and Ph.D. (2014) from Stony Brook University, NY. She was a postdoctoral researcher at Sorbonne Université, France (2014-2016) and is currently a research associate at Cornell University, NY. She is working on computational condensed matter physics using first principles calculations. In particular, her research is focused on understanding the effect of phonons on the atomic and electronic structure. In addition to being a researcher, she is a traveler, a hiker, and a dancer.

Project Title: 

Atomic and Electronic Structure of Nickelate Superconductors

Project Description: 

Recently superconductivity has been observed for the first time in a nickelate. In this project, we will explore the atomic structure of parent Ruddlesden-Popper (RP) phases R_n+1Ni_nO_3n+1 with R=La and high orders n=3,4,5 and/or explore the electronic structure of the oxygen-reduced phases R_n−1(NiO₂)_nR₂O₂ with R=La and high orders n=4,5.

Project question that defines the REU student's project:

What is the atomic structure of the parent RP nickelate phases and the electronic band structure of the oxygen-reduced nickelate phases?

Project plan/research task to answer the research question:

First principles methods, such as density functional theory (DFT), solve quantum mechanical systems at the level of electrons and atoms. DFT calculations provide information about ground state properties including atomic positions, lattice parameters, volume, bond lengths, electronic band structure, atomic forces, and phonon frequencies. Using the results of these calculations, it is possible to predict microscopic phenomena in a specific material. As an REU intern you will first learn how to use a DFT software package with your mentor. Once you have gained familiarity with the software and can run the simulations on your own, you will model the physical properties of a material of interest to a PARADIM project.

List of tasks to be performed by the REU student and tasks to be performed by the mentor to answer the research questions:

In particular, you will 1) learn the computational systems, for accessing, and using a computer cluster that has more computing power than your personal computer. 2)Then, you will learn how to use a DFT software package. Once you’re comfortable with running your calculations, you will 3) construct changes to the lattice and atomic structure for n=3 RP phase to make sure that we can obtain the experimentally-observed structure, 4) if successful, apply the same strategy to n=4,5 structures, 5) calculate the electronic band structure, 6) calculate the electronic band structure of the oxygen-reduced nickelate phases. I will be mentoring you to perform these simulations with an appropriate software package. We will hold meetings at least twice a week (Mondays and Fridays) via Zoom, and additional meetings as needed will be scheduled via Zoom. We will share files for results and analysis via a shared folder in Dropbox dedicated to you. I will provide you with further reading material, books, papers, and relevant videos to watch.