IMPRS Seminar: Spin Dynamics of Molecular Nanomagnets

Date

Jan 16, 2019

Time

1:00 PM - 2:00 PM

Speaker

Alessandro Chiesa

Affiliation

University of Parma

Series

IMPRS-MPSSE Seminar

Language

en

Main Topic

Physik

Other Topics

Physik

Description

Molecular Nanomagnets (MNMs) are at the forefront of current research and could constitute key elements of future spintronics devices, long-lasting nano-scale memories or scalable and noise-resilient quantum computing platforms. Furthermore, they are natural test-beds for investigating peculiar quantum phenomena [1]. In this talk I will present different techniques allowing us to obtain a deep insight into the spin dynamics of MNMs and show how this dynamics can be controlled in order to design quantum information processing units. On the experimental side, I will introduce the very powerful four-dimensional inelastic neutron scattering (4D-INS) technique [2] as an unrivalled tool to determine interactions in complex polycentric molecules and present its application to the paradigmatic Mn12 case [3]. Although it is the forefather of all MNMs, an unambiguous determination of even the leading magnetic exchange interactions was only possible by employing 4D-INS. This technique enables an atomic scale characterization of the molecular eigenstates, by portraying how individual spins fluctuate around the magnetic ground state. On the theoretical side, first principles methods offer the ideal tool to understand the origin and hierarchy of microscopic interactions and can be crucial to model anisotropic systems, where the competition between different interactions hinders the direct interpretation of experiments. I will present here our ab-initio DFT+Many-Body approach to determine the spin Hamiltonian [4] and study transport properties of MNMs, embedded in a molecular transistor architecture. This method allows us to evidence peculiar many-body effects in the prototypical Ni2 spin dimer. The richness in the spectrum of these systems can be exploited to design quantum information processing architectures, in which spin degrees of freedom are manipulated by electromagnetic pulses. I will present a few examples [5-7] in which the spin dynamics is controlled either by microwave (EPR) or by radio-frequency (NMR) pulses, enabling the implementation of quantum simulation and quantum error-correction algorithms. [1] Molecular Magnetic Materials: Concepts and Applications, edited by B. Sieklucka and D. Pinkowicz (Wiley-VCH, Weinheim, Germany, 2017). [2] Nature Phys. 8, 906-911 (2012) [3] Phys. Rev. Lett. 119, 217202 (2017) [4] Phys. Rev. Lett. 110, 157204 (2013) [5] Nature Commun. 7, 11377 (2016) [6] Chem. Sci. 9, 6183 (2018). [7] J. Am. Chem. Soc. 140, 9814-9818 (2018)

Last modified: Jan 16, 2019, 1:08:01 AM