COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER AND THE DEPARTMENT OF COMPUTATIONAL AND DATA SCIENCES – Understanding and controlling the magnetic exchange of novel materials – James Glasbrenner
COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER AND THE DEPARTMENT OF COMPUTATIONAL AND DATA SCIENCES (CSI 898-Sec 001)
Understanding and controlling the magnetic exchange of novel materials
Department of Computational and Data Sciences, and
Computational Materials Science Center
George Mason University
September 19, 2016, 4:30 pm
Exploratory Hall, Room 3301
The behavior of electrons in materials underpins key materials properties, which means that computing and understanding the electronic structure of various materials systems is of vital importance. These computations are, nowadays, often performed using density functional theory (DFT), a first-principles methodology that is an important tool in the computational materials scientist’s toolbox. One of the materials properties that is accessible via DFT is magnetism, and DFT can be used to study the magnetic interaction between electrons (called the exchange interaction) in a material. This involves constructing models such as the Heisenberg model and mapping DFT calculations onto it, which allows one to understand how tuning different features impacts important parameters such as the critical temperature and the stability of magnetic ground state. This approach to studying magnetic materials is of particular appeal in the spin electronics field, where the encoding and processing information using the magnetic states of electrons is of central importance. In this talk I will: 1) introduce the basic concepts of computational materials science using DFT in an accessible manner, and 2) present calculations on two different materials where I used DFT in conjunction with modeling to analyze the magnetic interactions. The first presented material will be the dilute magnetic semiconductor (Ba, K)(Zn, Mn)2As2, which exhibits ferromagnetism when a small amount of manganese and potassium are substituted into the material, and where changing the relative quantity of potassium influences the strength of the magnetic interactions. The second presented material is MnAu2, a magnetic metal that has a cork-screw noncollinear magnetic ground state which can be tuned in intriguing ways using pressure and chemical substitution. Using modeling in combination with DFT, I will show how we are able to understand the nature of the microscopic magnetic interactions in each material and that the microscopic mechanisms driving the the magnetic interactions in both compounds is the same. These results can then be used to resolve several experimental questions, one of which had gone unaddressed for several decades.
Refreshments will be served at 4:15 PM.
Find the schedule at http://www.cmasc.gmu.edu/seminars.htm