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We propose a simple, general, and accurate formula for analyzing the tunneling between classical configurations of a non-planar molecule in a gas medium, as a function of the thermodynamic parameters of the gas. We apply it to two…

Statistical Mechanics · Physics 2011-12-23 Mohammad Bahrami , Angelo Bassi

The magnetic properties of metal-organic complexes are strongly influenced by conformational changes in the ligand. The flexibility of Fe-tetra-pyridyl-porphyrin molecules leads to different adsorption configurations on a Au(111) surface.…

Mesoscale and Nanoscale Physics · Physics 2018-11-06 Daniela Rolf , Christian Lotze , Constantin Czekelius , Benjamin W. Heinrich , Katharina J. Franke

This chapter takes a microscopic view of quantum tunneling of magnetization (QTM) in single-molecule magnets (SMMs), focusing on the interplay between exchange and anisotropy. Careful consideration is given to the relationship between…

Mesoscale and Nanoscale Physics · Physics 2013-03-04 Junjie Liu , Enrique del Barco , Stephen Hill

A tunnel magnetic junction is considered with magnetic hard and magnetic soft layers of cubic symmetry. The magnetic switching is analyzed of the layers by a magnetic field perpendicular to the initial magnetizations. In such a situation,…

Materials Science · Physics 2009-08-11 S. G. Chigarev , E. M. Epshtein , P. E. Zilberman

We present a theory of tunneling spectroscopy of spin-selective Aharonov-Bohm oscillations in a lateral triple quantum dot molecule. The theory combines exact treatment of an isolated many-body system with the rate equation approach when…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Y. -P. Shim , F. Delgado , P. Hawrylak

Below 360 mK, Fe magnetic molecular clusters are in the pure quantum relaxation regime and we show that the predicted square-root time relaxation is obeyed, allowing us to develop a new method for watching the evolution of the distribution…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 W. Wernsdorfer , T. Ohm , C. Sangregorio , R. Sessoli , D. Mailly , C. Paulsen

We present a detailed study of the influence of various interactions on the spin quantum tunneling in a Mn12 wheel molecule. The effects of single-ion and exchange (spin-orbit) anisotropy are first considered, followed by an analysis of the…

Materials Science · Physics 2010-09-23 E. del Barco , S. Hill , C. C. Beedle , D. N. Hendrickson , I. S. Tupitsyn , P. C. E. Stamp

We theoretically investigate the effect of transverse magnetic anisotropy on spin-flip assisted tunneling through atomic spin chains. Using a phenomenological approach and first-order perturbation theory, we analytically calculate the…

Mesoscale and Nanoscale Physics · Physics 2017-05-17 J. Hageman , M. Blaauboer

Dissipative spin-tunneling transitions at biased resonances in molecular magnets such as Mn-12 Ac are controlled by the dipolar field that can bring the system on and off resonance. It is shown that this leads to spin relaxation in form of…

Statistical Mechanics · Physics 2012-01-10 D. A. Garanin

By event-driven molecular dynamics simulations we investigate magneto-transport in a two-dimensional model with randomly distributed scatterers close to the field-induced localization transition. This transition is generated by percolating…

Mesoscale and Nanoscale Physics · Physics 2015-12-14 Walter Schirmacher , Benedikt Fuchs , Felix Höfling , Thomas Franosch

While mesoscopic conducting loops are sensitive to external magnetic fields, as seen by observations of the Aharonov-Bohm (AB) effect in such structures, the field needed to observe the AB periodicity in small molecular rings is…

Mesoscale and Nanoscale Physics · Physics 2012-04-24 Dhurba Rai , Oded Hod , Abraham Nitzan

We investigate the topological quenching of spin tunneling in Mn_12-acetate molecules with an applied magnetic field along the hard axis. The model Hamiltonian describing this system has a fourth-order term due to the tetragonal anisotropy.…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Chang-Soo Park , Anupam Garg

Multi-spins tunneling cross-relaxations in an ensemble of weakly-coupled Ho$^{3+}$ ions, mediated by weak anisotropic dipolar interactions, can be evidenced by ac-susceptibility measurements in a high temperature regime. Based on a…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 R. Giraud , A. M. Tkachuk , B. Barbara

We present a theory of single-electron tunneling transport through a ferromagnetic nanoparticle in which particle-hole excitations are coupled to spin collective modes. The model employed to describe the interaction between quasiparticles…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 L. Michalak , C. M. Canali , V. G. Benza

Inspired by cotunneling spectroscopy of spin-states in a single OPE5-based molecule, we investigate the prospects for electric control of magnetism in purely organic molecules contacted in a three-terminal geometry. Using the gate…

Mesoscale and Nanoscale Physics · Physics 2012-12-21 J. Fock , M. Leijnse , K. Jennum , A. S. Zyazin , J. Paaske , P. Hedegård , M. Brøndsted Nielsen , H. S. J. van der Zant

We theoretically analyze the spectrum of a magnetic molecule when its charge and spin can couple to the molecular vibrations. More specifically, we show that the interplay between charge-vibron and spin-vibron coupling leads to a…

Mesoscale and Nanoscale Physics · Physics 2018-07-04 Ahmed Kenawy , Janine Splettstoesser , Maciej Misiorny

A model for single-domain uniaxial ferromagnetic particles with high anisotropy, the Ising model, is studied. Recent experimental observations have been made of the probability that the magnetization has not switched. Here an approach is…

Materials Science · Physics 2009-10-30 M. A. Novotny , M. Kolesik , P. A. Rikvold

The advent of milli-kelvin scanning tunneling microscopes (STM) with inbuilt magnetic fields has opened access to the study of magnetic phenomena with atomic resolution at surfaces. In the case of single atoms adsorbed on a surface, the…

Mesoscale and Nanoscale Physics · Physics 2012-06-19 Jean-Pierre Gauyacq , Nicolas Lorente , Frederico Dutilh Novaes

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…

Strongly Correlated Electrons · Physics 2009-11-11 C. Romeike , M. R. Wegewijs , H. Schoeller

Electron tunneling through a double quantum dot molecule, in the Kondo regime, under the effect of a magnetic field and an applied voltage, is studied. This system possesses a complex response to the applied fields characterized by a…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Gustavo. A. Lara , Pedro A. Orellana , Enrique V. Anda