U.S.-Ireland R&D Partnership: Molecular Magnetoelectric Materials

Florida State University, Tallahassee FL

Investigators

Abstract

Non-Technical Summary This collaborative project involving partners in the US, the Republic of Ireland and Northern Ireland, focuses on achieving molecular-level control of a new class of materials that possess both electric and magnetic properties that are readily switchable at ambient temperatures. The project is supported by the Solid State and Materials Chemistry program and the Condensed Matter Physics program, both in the Division of Materials Research. Of particular importance is the possibility to tune the coupling between the different material properties by choosing particular molecular building blocks, so that it becomes possible to switch, for example, the magnetic state with an external stimulus that would ordinarily switch only the electric property, and vice versa. This multi-functional behavior can potentially pave the way towards ultra-fast memory storage applications with very low energy consumption, thereby solving one of the most significant roadblocks to the continued miniaturization of electronic devices (Moore’s law). Research activities focus on chemical synthesis, precise characterization of the resulting materials, and routes towards fabrication of nanoscale device structures. Impacts are therefore expected at several levels, chiefly in terms of transformative fundamental science, but also increased understanding of molecular design principles leading to new technologies for the 21st century. The highly interdisciplinary and transnational consortium provides excellent training and mobility opportunities to early stage PhD and postdoctoral researchers, and a target of 40-60% female participation among the funded teams will promote gender equality. The tripartite US-Ireland consortium also ensures meaningful cross-border collaboration between teams on the island of Ireland, North and South, thereby working towards the twin goals of building prosperity and an all-island economy and continuing the work of peace and reconciliation between the two jurisdictions. Technical Summary This collaborative project, supported by the Solid State and Materials Chemistry program and the Condensed Matter Physics program, both in the Division of Materials Research, sets out routes to harness the switchable electronic spin states that occur in certain paramagnetic transition metal complexes for development of a new class of magnetoelectric materials. The target compounds are spin crossover metal-organics which can change their internal arrangement of electrons in d-orbitals from paired to unpaired with heat, photoexcitation, pressure/strain or electric and magnetic fields. The project examines the interplay between changes in electric, magnetic and structural properties that accompany the spin state switching under a range of perturbations. Routes to robust nanofabrication of the crystalline metal-organics are also explored. Four interdisciplinary sub-projects are investigated: (1) Optimization of synthetic routes to ensure (i) crystallization in a polar ferroelectric space group and (ii) retention of thermal spin state switching; (2) Characterization of (i) the spin state and (ii) the ferroelectric domain structure; (3) Potential for magnetic, electric, optical and strain switching of spin state and electric polarization; and (4) Nanofabrication of the metal-organics from crystals into arrays on thin films. The focus on molecule-based metal-organics with soft lattices offers an alternative and advantageous pathway towards materials with magnetic and electric polarization responses that are readily switchable at room temperature, with future potential for ultra-fast, low energy memory applications. 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.