Spin quantum tunneling in single molecular magnets: fingerprints in transport spectroscopy of current and noise

We demonstrate that transport spectroscopy of single molecular magnets shows signatures of quantum tunneling at low temperatures. We find current and noise oscillations as function of bias voltage due to a weak violation of spin selection rules by quantum tunneling processes. The interplay with Boltzmann suppression factors leads to fake resonances with temperature-dependent position which do not correspond to any charge excitation energy. Furthermore, we find that quantum tunneling can completely suppress transport if the easy-plane anisotropy has a high symmetry.Comment: 4 pages, 3 figure

Quantum tunneling induced Kondo effect in single molecular magnets

We consider transport through a single-molecule magnet strongly coupled to metallic electrodes. We demonstrate that for half-integer spin of the molecule electron- and spin-tunneling \emph{cooperate} to produce both quantum tunneling of the magnetic moment and a Kondo effect in the linear conductance. The Kondo temperature depends sensitively on the ratio of the transverse and easy-axis anisotropies in a non-monotonic way. The magnetic symmetry of the transverse anisotropy imposes a selection rule on the total spin for the occurrence of the Kondo effect which deviates from the usual even-odd alternation.Comment: 4 pages, 4 figure

Kondo-transport spectroscopy of single molecule magnets

We demonstrate that in a single molecule magnet (SMM) strongly coupled to electrodes the Kondo effect involves all magnetic excitations. This Kondo effect is induced by the quantum tunneling of the magnetic moment (QTM). Importantly, the Kondo temperature $T_K$ can be much larger than the magnetic splittings. We find a strong modulation of the Kondo effect as function of the transverse anisotropy parameter or a longitudinal magnetic field. For both integer and half-integer spin this can be used for an accurate transport spectroscopy of the magnetic states in low magnetic fields on the order of the easy-axis anisotropy parameter. We set up a relationship between the Kondo effects for successive integer and half-integer spins.Comment: 5 pages, 3 figure

Vulnerability and Trust in Leader-Follower Relationships

Purpose – Vulnerability is a concept that lies at the core of the most prevalent academic trust definitions. Accordingly, a vast amount of scholars refers to vulnerability when studying trust. Surprisingly, there is almost no conceptual nor empirical work explicitly directed at understanding vulnerability itself. The purpose of this paper is to summarize and critique the existing base of knowledge of vulnerability with a particular focus on the leader-follower relationship and to open avenues for future research. Design/methodology/approach – In the process of a very systematic literature search, the authors identified 49 studies that refer to vulnerability when studying trust at the interpersonal level. The authors coded the literature into conceptualizations, antecedents and consequences of vulnerability – with a particular focus on the leader-follower relationship. Findings – The authors introduce a theoretical framework which allows the authors to structure the rather fuzzy discussed concept of vulnerability. The development of such a theoretical framework allows the authors to distinguish between trusting beliefs and actual trusting behaviour so that it is possible to separate the constructs of willingness-to-be-vulnerable and actual vulnerability. Research limitations/implications – With the help of the developed framework, the authors point to the need for more work on vulnerability in order to take the study of trust to the next level. In this respect, the authors formulate several propositions that should be tested in future research. Practical implications – Practitioners are made aware of the need to risk willingness to be vulnerable as a base for trusting behaviour. There is no way around being willing to be vulnerable. Originality/value – This literature review provides a holistic understanding of the concept of vulnerability. The intention is to show the different understandings and interpretations of this term within the literature and identify which antecedents and consequences are related to the concept of vulnerability. </jats:sec

Electron transport through single Mn12 molecular magnets

We report transport measurements through a single-molecule magnet, the Mn12 derivative [Mn12O12(O2C-C6H4-SAc)16(H2O)4], in a single-molecule transistor geometry. Thiol groups connect the molecule to gold electrodes that are fabricated by electromigration. Striking observations are regions of complete current suppression and excitations of negative differential conductance on the energy scale of the anisotropy barrier of the molecule. Transport calculations, taking into account the high-spin ground state and magnetic excitations of the molecule, reveal a blocking mechanism of the current involving non-degenerate spin multiplets.Comment: Accepted for Phys. Rev. Lett., 5 pages, 4 figure