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Magnetic switching of a single molecular magnet (SMM) due to spin-polarized current flowing between ferromagnetic metallic electrodes is investigated theoretically. Magnetic moments of the electrodes are assumed to be collinear and parallel…

Mesoscale and Nanoscale Physics · Physics 2016-08-16 Maciej Misiorny , Józef Barnas

The mechanisms of thermally activated magnetization switching in small ferromagnetic particles driven by an external magnetic field are investigated. For low uniaxial anisotropy the spins rotate coherently while for sufficiently large…

Statistical Mechanics · Physics 2009-10-31 U. Nowak , D. Hinzke

Magnetization measurements of a molecular clusters Mn12 with a spin ground state of S = 10 show resonance tunneling at avoided energy level crossings. The observed oscillations of the tunnel probability as a function of the magnetic field…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 W. Wernsdorfer , M. Soler , G. Christou , D. N. Hendrickson

We report measurements and theoretical analysis of resonant spin tunneling in randomly oriented nanospheres of a molecular magnet. Amorphous nanospheres of Mn$_{12}$ acetate have been fabricated and characterized by chemical, infrared, TEM,…

Mesoscale and Nanoscale Physics · Physics 2015-07-30 S. Lendinez , R. Zarzuela , J. Tejada , M. W. Terban , S. J. L. Billinge , J. Espin , I. Imaz , D. Maspoch , E. M. Chudnovsky

The synthesis of molecular magnets has undergone rapid progress in recent years. Each of the identical molecular units can contain as few as two and up to several dozens of paramagnetic ions (spins). Although these materials appear as…

Strongly Correlated Electrons · Physics 2009-11-11 J. Schnack

We review the present state of theory and experiments on the quantum tunneling of magnetization in mesoscopic spin systems. Most attention is paid to the relaxation of magnetization in the molecular complexes Mn12 and Fe8. The role of the…

Condensed Matter · Physics 2007-05-23 Igor Tupitsyn , Bernard Barbara

We present a method for precisely measuring the tunnel splitting in single-molecule magnets using electron-spin resonance, and use these measurements to precisely and independently determine the underlying transverse anisotropy parameter,…

Mesoscale and Nanoscale Physics · Physics 2016-12-13 Charles A. Collett , Rafael A. Allão Cassaro , Jonathan R. Friedman

A new quantum approach is presented that can account for the description of small ferromagnetic particles magnetization tunneling. An estimate of the saturation value of an external applied magnetic field along the easy axis is obtained. An…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 D. Galetti , B. M. Pimentel , C. L. Lima , E. C. Silva

We present a new family of exchange biased Single Molecule Magnets in which antiferromagnetic coupling between the two components results in quantum behaviour different from that of the individual SMMs. Our experimental observations and…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 W. Wernsdorfer , N. Aliaga-Alcalde , R. Tiron , D. N. Hendrickson , G. Christou

In the last years there has been a great interest in magnetic systems formed by a cluster of transition metal ions covalently bonded via superexchange bridges, embedded in a large organic molecule. Following the synthesis and the structural…

Materials Science · Physics 2007-05-23 F. Borsa , A. Lascialfari , Y. Furukawa

The quantum tunneling of the magnetization vector are studied theoretically in single-domain ferromagnetic nanoparticles placed in an external magnetic field at an arbitrarily directed angle in the $ZX$ plane. We consider the…

Statistical Mechanics · Physics 2009-10-31 Rong Lu , Jia-Lin Zhu , Zhi-Rong Liu , Lee Chang , Bing-Lin Gu

We present high-frequency angle-dependent EPR data for crystals of [NixZn1-x(hmp)(t-BuEtOH)Cl]4 (x = 1 and 0.02). The x = 1 complex behaves as a single-molecule magnet at low temperatures, displaying hysteresis and exceptionally fast…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 C. Kirman , J. Lawrence , S. Hill , E-C. Yang , D. N. Hendrickson

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…

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

The discovery a decade ago that individual molecules can function as magnetizable magnets provided a new, 'bottom-up' approach to nanoscale magnetic materials, and such molecules have since been called single-molecule magnets (SMMs). Each…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. J. Tasiopoulos , A. Vinslava , W. Wernsdorfer , K. A. Abboud , G. Christou

A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 A. Morello , A. Millán , L. J. de Jongh

We consider tunneling transport through a Mn$_{12}$ molecular magnet using spin density functional theory. A tractable methodology for constructing many-body wavefunctions from Kohn-Sham orbitals allows for the determination of…

Mesoscale and Nanoscale Physics · Physics 2010-02-08 L. Michalak , C. M. Canali , M. R. Pederson , M. Paulsson , V. G. Benza

Many molecular magnetic clusters, such as single-molecule magnets, are characterized by spin ground states with defined total spin S exhibiting zero-field-splittings. In this work, the spectroscopic intensities of the transitions within the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 O. Waldmann , H. U. Güdel

Spin coherent state path integrals with discontinuous semiclassical paths are investigated with special reference to a realistic model for the magnetic degrees of freedom in the Fe8 molecular solid. It is shown that such paths are essential…

Condensed Matter · Physics 2009-11-07 Ersin Kececioglu , Anupam Garg

We examine theoretically electron paramagnetic resonance (EPR) lineshapes as functions of resonance frequency, energy level, and temperature for single crystals of three different kinds of single-molecule nanomagnets (SMMs): Mn$_{12}$…

We show that the nuclear spin dynamics in the single-molecule magnet Mn12-ac below 1 K is governed by quantum tunneling fluctuations of the cluster spins, combined with intercluster nuclear spin diffusion. We also obtain the first…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Andrea Morello , Oleg N. Bakharev , Hans B. Brom , Roberta Sessoli , L. Jos de Jongh