Title

Phase Transitions of an Anisotropy Ising-O(3) Model

Presenter Information

Anzumaan Chakraborty

Department

Physics

Major

Physics

Research Advisor

Vojta, Thomas

Advisor's Department

Physics

Funding Source

National Science Foundation

Abstract

The two-dimensional anisotropic Ising-O(3) model is an effective Hamiltonian for the square-lattice J1-J2 Heisenberg model, with nearest-neighbor coupling J1 along with frustrated and dominant next-nearest-neighbor coupling J2. We employ Monte Carlo simulation of the Ising-O(3) model to determine its phase diagram as a function of the anisotropy of the O(3) spins and the temperature. For sufficiently large anisotropy, there is a direct transition from the paramagnetic high-temperature phase to the low-temperature phase that breaks both spin and nematic (Ising) symmetries. This transition splits into two separate transitions as the anisotropy is lowered, leading to the appearance of an Ising-ordered intermediate phase. We also determine the orders of the phase transitions. These results can be related to the experimental observations of the orders and sequences of magnetic and structural transitions in quasi-2D ferropnictide materials.

Biography

Anzumaan is a junior with a major in both physics and mathematics. Anzumaan worked with Dr. Vojta on this project for three semesters as well as during the summer of 2018. He is currently interested in pursuing a PhD in theoretical physics after graduating to become a professor and researcher. Outside of academics, Anzumaan has an active role in Society of Physics Students, College Democrats, and the Missouri S&T Math Team.

Research Category

Sciences

Presentation Type

Poster Presentation

Document Type

Poster

Location

Upper Atrium

Presentation Date

16 Apr 2019, 9:00 am - 3:00 pm

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Apr 16th, 9:00 AM Apr 16th, 3:00 PM

Phase Transitions of an Anisotropy Ising-O(3) Model

Upper Atrium

The two-dimensional anisotropic Ising-O(3) model is an effective Hamiltonian for the square-lattice J1-J2 Heisenberg model, with nearest-neighbor coupling J1 along with frustrated and dominant next-nearest-neighbor coupling J2. We employ Monte Carlo simulation of the Ising-O(3) model to determine its phase diagram as a function of the anisotropy of the O(3) spins and the temperature. For sufficiently large anisotropy, there is a direct transition from the paramagnetic high-temperature phase to the low-temperature phase that breaks both spin and nematic (Ising) symmetries. This transition splits into two separate transitions as the anisotropy is lowered, leading to the appearance of an Ising-ordered intermediate phase. We also determine the orders of the phase transitions. These results can be related to the experimental observations of the orders and sequences of magnetic and structural transitions in quasi-2D ferropnictide materials.