Quantum Crystallography in molecular magnetism

Jacob Overgaard, Aarhus University

Molecular magnetism is a generic term that encompasses all molecular constructs having magnetic properties of some type. Thus, it covers spin cross-over systems, spintronics and molecular nanomagnets, to name just a few. The magnetic properties are obviously controlled by the unpaired electrons in the system, and given the fact that quantum crystallography (QCr) at its core exploits diffraction methods that reveal details of the electron density distribution, both the total and the spin-resolved density, we are ideally suited to probe magnetic properties with QCr tools.

In this presentation, I will focus on the application of QCr to the study of molecular nanomagnets (MNM). MNMs are molecular coordination compounds that below a blocking-temperature exhibits a hysteresis loop, i.e. the magnetization vs magnetic field curve opens up and conveys a memory effect to this class of materials. Naturally, this observation has triggered a lot of attention as it may be useful as extremely small memory bits, or in a more advanced application take the role as qubits in quantum computing.

In this talk, I will specifically explain how we in my research group at Aarhus University have used synchrotron X-ray diffraction to first derive the electron density distribution in a range of MNMs and subsequently used this knowledge to calculate important parameters of high relevance for the function of MNMs. If time allows, I will also explain how polarized neutron diffraction can be used to reveal complementary information about the magnetic properties in MNMs.