CAREER: Symmetry designed spin currents: broadening the spintronics materials palette

Brown University, Providence RI

Investigators

Abstract

Nontechnical description This project will explore a new class of materials for energy-efficient data processing and storage by harnessing the spin of electrons rather than their electric charge. Traditional microelectronics face increasing energy demands and shrinking size limits. Spin-based devices, on the other hand, can potentially run with lower power and higher performance. However, managing the direction of electron spins becomes essential at very small scales. To address this, the research team will design oxide crystals with carefully tuned symmetries, enabling spin currents to be generated in the exact orientation needed for switching tiny magnetic bits. By enlarging the pool of materials that can perform this function, the project aims to spark development of more compact, faster, and energy-conscious computing technologies. In addition, an integrated educational component will strengthen undergraduate instruction in materials science and offer lab-based experiences for students, cultivating broader skillsets in next-generation hardware design. Technical description This project will systematically investigate the generation of out-of-plane spin-polarized currents in anisotropic oxide thin films grown by pulsed laser deposition. The principal investigator will fabricate epitaxial bilayer heterostructures in which a crystalline oxide with strong spin-orbit coupling is interfaced with a magnetic layer capable of detecting and switching in response to spin signals. By controlling substrate orientation and strain conditions, the team will establish precise crystal symmetries that break conventional spin-current constraints, allowing a charge flow to produce a spin polarization component oriented perpendicular to the film plane. The research team will quantify spin-torque efficiency by combining spin-torque ferromagnetic resonance and harmonic Hall measurements under varied temperatures, film thicknesses, and anisotropic strain states. These data will clarify the role of crystal symmetry in determining the magnitude and direction of spin polarization. In addition, the research will integrate correlated electron states, such as polar or superconducting phases, to uncover new functionalities that arise when out-of-plane spin currents coexist with these effects. Overall, this project will provide a framework for expanding the materials palette used in advanced spin-based logic and memory technologies, with broad implications for future electronic and photonic materials research. 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.