High throughput screening of materials for passive radiative cooling purposes
In this work, we performed high-throughput screening (Python) of 1500+ candidate materials for passive radiative cooling by extracting key properties from ABINIT-generated datasets and computing optical emissivity using physics-based models.
Discovering critical film thickness driven antiferroelectricty in otherwise ferroelectric system
In this work, we used Effective Hamiltonian based monte carlo model for multiferroic BFO to predict the relative stability of antiferroelectricty as the ground state below a critical thickness. It was found that as thickness decreased, the short range forces that inhibit ferroelectricity increased while the long range forces contribution decreased thereby making antiferroelectricty relatively more stable than ferroelectricity.
Phase modeling in BaTiO3 / SrTiO3 thin films
In this work, we guided experimental collaborators in narrowing candidate set by modelling and identifying multiphase coexistence composition using Landau-Ginzburg-Devonshire theory (Python), helping collaborators synthesize high-dielectric tunability BaxSr1-xTiO₃ (BST) alloy thin films.
Changes in spin cycloidal structure in doped BixLa1-xFeO3
Bismuth Ferrite in its ground state form is ferroelectric and antiferromagnetic (AFM). Its AFM however is modulated by a spin cycloid wave that spans ~62 nm in its period. Thus, the magnetic structure of BFO can exist between an AFM and a cycloid (with various possible cycloid propagation directions) or both. In this work, we studied the relative stability of different magnetic structures in doped BFO as a function of La composition.
Magnetic structure under uniaxial strain
This project was a joint venture of Prof. Maximilien Cazayous at the University of Paris and the group of Prof. Laurent Bellaiche at UArk, US. In this work we predicted how the magnetic structure (competition between the cycloid and G-type AFM), the polar structure (orientation of polar displacements), and the oxygen octahedral tilts change when the Bismuth Ferrite system (periodic in all three directions i.e., bulk) is strained uniaxially. The effective Hamiltonian was able to show the uncoupling of the response of magnetic and polar structure, which also validated experiments.
Polar topological defects in BFO/STO superlattices
BFO: Bismuth Ferrite is a room temperature multiferroic ie., it shows both ferroelectric and antiferromagnetic properties at room temperature. This makes it unique. In this project, experimentalists at UNSW Sydney desgined BFO/STO (SrTiO3) superlattice thin films. The presence of STO lead to BFO be under interesting conditions. To simulate this, we changed the electrical and mechanical boundary conditions that the BFO film was under. This created interesting topological polar defects (meron), hence validating experiments.
Characterization of relaxor ferroelectric single crystals
Relaxor ferroelectrics have the characteristic property of relaxed dielectric dispersion. These materials are argued not to have a conventional domain structure like other ferroelectrics, sometimes explained as having polar nano regions while other theories explain using exceptionally large number of domain walls. Either way, this response can be studied using diffuse scattering. Diffuse scattering is diffuse intensity around actual Bragg peaks. In this project, we related the shapes of the diffuse scattering intensity and the changes in those shapes with external stimuli (in this case – electric field and stress) to the change in domain structure in PMN-PT crystals under tge effects of external stimuli. This work was in collaboration with US Naval Research Laboratory.
Ferroelectric domain continuity in 3-dimensional polycrystals
This project is about investigating the probability with which ferroic domains can continue across a microstructure. Why one could ask. Since the 1950s, polycrystals with continuous domains have been observed experimentally. But not much research was done to check when is it likely and what do materials scientists need to ensure in order to make this possible. This was a long project that started as my Ph.D. project at UNSW Sydney. In this work, we started out as a stereographic project based framework on bicrystals, and formulated polar and plane matching condition to simulate domain contintuiy. Surprising was the result that domain planar continuty was not that improbable given the correct conditions. Nature ofcourse showed us that in the previously mentioned empirical observations. This was then extended to modelled polycrystals with random, preferred, textured grain and grain boundary orientations, and an extensive statistical study was undertaken.
Smart and visualization friendly approach to predict domain walls in ferroelectrics
The task to calculate the domain walls in established symmetries include tedious solving of equatuions. In this work, we developed a smart, efficient, future looking and visualization friendly approach to predict permissible domain walls in ferroelectric symmetries without full scale equation solving. It worked by modeling charge neutrality and strain matching. The visualization was done using stereographic projection. Through this method, in addition to fixed domain walls (i.e., walls that are fixed in their orientation), but also variable domain walls (walls whose orientation is a function of external stimuli like electric field or temperature) could also be predictyed. In addition their motion (here motion means change in orientation) could also be easily visualized on the same stereographic projection.
Sukriti Mantri 