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Electronically Mediated Magnetic Anisotropy in Vibrating Magnetic Molecules
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.ORCID iD: 0000-0002-9217-2218
2018 (English)In: ACS Omega, E-ISSN 2470-1343, Vol. 3, no 6, p. 6546-6553Article in journal (Refereed) Published
Abstract [en]

We address the electronically induced anisotropy field acting on a spin moment comprised in a vibratingmagnetic molecule located in the junction between ferromagnetic metals. Under weak coupling between theelectrons and molecular vibrations, the nature of the anisotropy can be changed from favoring a high spin (easyaxis) magnetic moment to a low spin (easy plane) by applying a temperature difference or a voltage bias acrossthe junction. For unequal spin-polarizations in the ferromagnetic metals it is shown that the character of theanisotropy is essentially determined by the properties of the weaker ferromagnet. By increasing the temperaturein this metal, or introducing a voltage bias, its influence can be suppressed such that the dominant contributionto the anisotropy is interchanged to the stronger ferromagnet. With increasing coupling strength between themolecular vibrations and the electrons, the nature of the anisotropy is locked into favoring easy plane magnetis

Place, publisher, year, edition, pages
2018. Vol. 3, no 6, p. 6546-6553
National Category
Atom and Molecular Physics and Optics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-348657DOI: 10.1021/acsomega.8b00449ISI: 000436340500071OAI: oai:DiVA.org:uu-348657DiVA, id: diva2:1198139
Funder
Swedish Research CouncilAvailable from: 2018-04-16 Created: 2018-04-16 Last updated: 2018-09-17Bibliographically approved
In thesis
1. Probing Magnetism at the Atomic Scale:  Non-Equilibrium Statistical Mechanics Theoretical Treatise
Open this publication in new window or tab >>Probing Magnetism at the Atomic Scale:  Non-Equilibrium Statistical Mechanics Theoretical Treatise
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Here, I present a theoretical study, based on non-equilibrium quantum statistical mechanics and on the non-equilibrium extension to the RKKY intveraction,where I investigate the emergence of magnetism at the atomic scale in adsorbed molecular complexes hosting localized spin moments, at the stake of being probed with scanning tunneling microscopy tip, and being driven by a temperature gradient and gated by an electric field. The scanning tunneling microscopy set up is modeled as a molecular junction with a magnetic molecule embedded within it, where the molecule consists in a set of electronic levels resembling the typical s-p orbitals of a metal hydride or an organometal, and a localized spin moment resembling the magnetic unit hosted by the latter and former type of molecules mentioned. The electronic levels and the magnetic units are coupled via the Kondo interaction. One of the electrodes in the junction plays the role of an scanning tunneling microscopy tip, and the other one, does it for the metal in which the molecule is adsorbed, and a bias voltage and a temperature gradient is applied across both metals, giving rise to the effect of the above mentioned experimental set up and producing electrical, spin, energy and heat currents as a response, providing the possibility to predict experimentally observed quantities such as differential conductivities. Throughout the thesis, I present first a comprehensive introduction to the topic pointing out its relevance, the experimental context in which the work I append lies and I as well present the formal structure of the work I present. The upcoming chapters, lead the audience to the discussion of the non-equilibrium formalism in atomic, molecular and condensed matter physics, paying special attention on the subject on magnetism, and putting in to context the molecular system where the interplay, among electrons, spins and phonons is relevant. To wrap up the theoretical discussion I described the state of the art progress on quantum coherence and interferometry in molecular junctions and locate my contribution into this context. Then I conclude and summarize. My contribution promises to pave the way to more robust spin based quantum engineered technology.

 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 205
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1678
Keywords
Non-Equilibrium Statistical Mechanics, Magnetism, Quantum Optics, Quantum Coherence, RKKY, Colciencias, Equation of Motion, Jauho-Meir-Wingreen Formalism
National Category
Atom and Molecular Physics and Optics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics; Physics with specialization in Quantum Chemistry; Physics and Astronomy specializing in Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-349238 (URN)978-91-513-0353-6 (ISBN)
Public defence
2018-06-14, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 2, Uppsala, 13:31 (English)
Opponent
Supervisors
Available from: 2018-05-23 Created: 2018-04-24 Last updated: 2018-09-27

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Jaramillo, Juan David VasquezHammar, HenningFransson, Jonas

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