Dinuclear Metal Tetracarboxlates Molecule-based Magnets

University Of Utah, Salt Lake City UT

Investigators

Abstract

TECHNICAL SUMMARY: Elucidation of the fundamental science by establishing structure-function relationships to identify new magnets with technologically important properties and exploiting the anomalous magnetic properties we already discovered for ruthenium-based magnets is goal of this project. The targeted properties include: including enhanced ordering temperatures (Tc), controllable coercive fields (Hcr), and to extend and exploit their anomalous magnetic properties. The [Ru2(O2CMe)4]3[Cr(CN)6] magnet (Tc = 33 K) has 2 interpenetrating lattices that lead to anomalous hysteresis and zero-field cooled/field cooled magnetization etc. Its Tc reversibly increases by 79% to 59 K with applied pressure, and the anomalous wasp-waist shaped hysteresis becomes normal at 12.8 kbar. Identifying the genesis and extending and exploiting the magnetic consequences of the interpenetrating lattice for this family of magnets are targeted. The 2nd lattice leads to anomalous behaviors, and it is a rare example of new phenomena arising from a 2nd lattice. New examples with higher Tc and coercivity controllable by pressure will be identified. Magnets composed of [FeII/III2(O2CR)4]+ (S = 9/2), [Ru2(O2CR)4]n (n = 0, 2+), [Ru(CN)6]3-, [Os2(O2CR)4]+, and [M(NCS)6]3- composition are sought. Also, control of the sign of spin coupling (J) to observe ferromagnetic not ferrimagnetic coupling will be validated by making and studying [M2(O2CMe)4]3[Cr(CN)6] (M = Rh, Mo). This work is supported by the Solid State and Materials Chemistry program in the Division of Materials Research at the NSF. NON-TECHNICAL SUMMARY: Magnetism is scientifically and technologically exceedingly important as it is the basis of a $20-billion/yr industry. Organic-based magnets enable the development of new families of magnets with combinations of properties not previously observed as well as providing a deeper and broader understanding of magnetism to form a stronger foundation for next-generation materials and devices. Control of magnetic behavior via structure control, especially for interpenetrating structures, will lead to the development of new and enhanced properties for future hybrid multifunctional materials. Developing and exploiting new materials is key to next generation devices, and is essential for the training of undergraduate students, graduate students, and post-doctoral scholars in many interdisciplinary aspects of materials chemistry with emphasis on the design, synthesis, chemical, and magnetic characterization of a new class of magnets. This research endeavor lends itself to outreach activities such as talks with audience participation to K-12 students and community audiences, as well as having minority high school and undergraduate students participate in research activities and assist journalists with their reports on technical topics. The study of new magnetic materials is a worldwide enterprise, and existing worldwide collaborations with scientists in the UK, Spain, Russia, Korea, Japan, and Greece will be strengthened and expanded. This work is supported by the Solid State and Materials Chemistry program in the Division of Materials Research at the NSF.