Manipulation of single spins in ferroelectric oxides from first principles

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NONTECHNICAL SUMMARYThis award supports research into materials that may provide new ways to store or process information. In computers, information is encoded in a sequence of bits, each of which can have a value of 0 or 1. Implementing these bits physically requires a system that can be switched between two possible states, such as on/off or up/down. One of the smallest platforms for storing and processing information is a quantum mechanical property of electrons called “spin”, which can take on two possible values (up/down). However, controlling these single spins is challenging, because it is difficult to attach control knobs to electrons.This project will explore ferroelectric oxide materials containing dilute concentrations of magnetic dopant atoms as a system for realizing single spin control. Ferroelectrics are materials that exhibit a spontaneous electrical polarization, the direction of which can be reversed by applying an electric field. When an isolated magnetic dopant atom is inserted into the ferroelectric, the local spatial environment of the magnetic dopant atom impacts the direction of its spin. Furthermore, electric field-based polarization reversal changes the local spatial environment in a ferroelectric crystal, and hence has the potential to modify the spin’s direction. The goal of this project is to understand how to manipulate the direction of magnetic spins inserted into a series of ferroelectric oxide materials by utilizing a combination of quantum mechanical computer simulations and theoretical symmetry analysis.This scientific research will be complemented by efforts to increase the diversity of students and researchers participating in the materials science and engineering discipline. In particular, via research collaborations this project will increase the exchange of students and scientific ideas between the University of California, Merced, which serves a large number of students who are underrepresented minorities and/or first-generation college students, and Lawrence Berkeley National Laboratory. In addition, the training of a postdoctoral researcher will contribute to scientific workforce development.TECHNICAL SUMMARYThis award supports theoretical and computational research on the manipulation of single spins – one of the smallest platforms to store and process information – with electric fields. The project will focus on magnetic dopant atoms inserted into ferroelectric oxide host crystals as a platform to realize and explore this concept. The preferred orientation of a spin is connected to its local crystallographic environment via the spin-orbit interaction. In a ferroelectric, this local environment can be modified by structural changes that occur during polarization switching under applied electric fields, which provides a path towards the electric field control of the spin directionality. In addition, tuning a ferroelectric to near a structural phase transition may further facilitate abrupt electric field-induced changes to spin orientation. Using a combination of density functional theory calculations and group theory analysis, this project will advance fundamental understanding of electric field-based single spin manipulation in a series of perovskite and hexagonal oxide ferroelectrics. The project will also explore the directionality of single spins inserted in topological defects in ferroelectrics, such as domain walls and vortex structures.This scientific research will be complemented by activities geared toward increasing the diversity of students and researchers participating in the materials science and engineering discipline. These activities will focus on increasing the exchange of students and scientific ideas between the University of California, Merced, which serves a large number of students who are underrepresented minorities and/or first-generation college students, and Lawrence Berkeley National Laboratory. In addition, the training of a postdoctoral researcher as a part of this project will contribute to scientific workforce development.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.