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Single molecule magnets (SMMs) with single-ion anisotropies $\mathbf d$, comparable to exchange interactions J, between spins have recently been synthesized. In this paper, we provide theoretical insights into the magnetism of such systems.…

Strongly Correlated Electrons · Physics 2017-11-22 Sumit Haldar , Rajamani Raghunathan , Jean-Pascal Sutter , S. Ramasesha

We present a theoretical approach to calculate the molecular magnetic anisotropy parameters, $D_M$ and $E_M$ for single molecule magnets in any eigenstate of the exchange Hamiltonian, treating the anisotropy Hamiltonian as a perturbation.…

Strongly Correlated Electrons · Physics 2009-11-13 Rajamani Raghunathan , S. Ramasesha , Diptiman Sen

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

We study single-ion and exchange anisotropy effects in equal-spin $s_1$ tetramer single molecule magnets exhibiting $T_d$, $D_{4h}$, $D_{2d}$, $C_{4h}$, $C_{4v}$, or $S_4$ ionic point group symmetry. We first write the group-invariant…

Strongly Correlated Electrons · Physics 2009-11-13 Richard A. Klemm , Dmitri V. Efremov

To understand the effect of molecular environment on the electronic and magnetic properties of the single-molecule magnet (SMM) Mn$_{12}$, we explore two possible means for adding extra electrons to molecule. We explore both substitution of…

Materials Science · Physics 2009-11-10 Kyungwha Park , Mark R. Pederson

We present a review of recent advances in the study of many-body effects in magnetic nanoparticles. Considering classical spins on a lattice coupled by the exchange interaction in the presence of the bulk and surface anisotropy, we…

Statistical Mechanics · Physics 2016-08-31 H. Kachkachi , D. A. Garanin

The spin-orbit interaction in semiconductors is shown to result in an anisotropic contribution into the exchange Hamiltonian of a pair of localized conduction-band electrons. The anisotropic exchange interaction exists in semiconductor…

Condensed Matter · Physics 2009-10-31 K. V. Kavokin

The properties of quantum systems interacting with their environment, commonly called open quantum systems, can be strongly affected by this interaction. While this can lead to unwanted consequences, such as causing decoherence in qubits…

Magnetic materials are usually characterized by anisotropy energy barriers which dictate the time scale of the magnetization decay and consequently the magnetic stability of the sample. Here we present a unified description, which includes…

Statistical Mechanics · Physics 2014-03-31 F. Borgonovi , G. L. Celardo

We investigate the far-from-equilibrium nature of magnetic anisotropy and exchange interactions between molecular magnets embedded in a tunnel junction. By mapping to an effective spin model, these magnetic interactions can be divided into…

Mesoscale and Nanoscale Physics · Physics 2015-01-08 Jonas Fransson , Jie Ren , Jian-Xin Zhu

Motivated by the recent suggestion of anisotropic effective exchange interactions between Mn spins in Ga$_{1-x}$Mn$_x$As (arising as a result of spin-orbit coupling), we study their effects in diluted Heisenberg spin systems. We perform…

Disordered Systems and Neural Networks · Physics 2007-05-23 Chenggang Zhou , Malcolm P. Kennett , Xin Wan , Mona Berciu , R. N. Bhatt

Mapping the magnetic exchange interactions from model Hamiltonian to density functional theory is a crucial step in multi-scale modeling calculations. Considering the usual magnetic force theorem but with arbitrary rotational angles of the…

Materials Science · Physics 2010-11-23 Samir Lounis , Peter H. Dederichs

Magnetic properties of a tetrahedral "Ni_4" molecule are discussed in terms of the Heisenberg model, with magnetic anisotropy terms included, and on the basis of first-principle calculations within the density functional theory. It is shown…

Materials Science · Physics 2007-05-23 A. V. Postnikov , M. Brueger , J. Schnack

The effect of dipolar interaction and local uniaxial anisotropy on the magnetic response of small spin clusters where spins are located on the vertices of icosahedron, cuboctahedron, tetrahedron and square geometry have been investigated.…

Atomic and Molecular Clusters · Physics 2012-01-11 Alfred Hucht , Sanjubala Sahoo , Shreekantha Sil , Peter Entel

We study the modification of low temperature properties of quantum magnets such as magnetization, heat capacity, energy spectrum, and densities of condensed and noncondensed quasiparticles (triplons) due to anisotropies in the framework of…

Statistical Mechanics · Physics 2021-11-05 Abdulla Rakhimov , Asliddin Khudoyberdiev , Bilal Tanatar

We investigate the effect of coupling (intensity and nature), applied field, and anisotropy on the spin dynamics of a multi-layer system composed of a hard magnetic slab coupled to a soft magnetic slab through a nonmagnetic spacer. The soft…

Materials Science · Physics 2015-06-12 Andres Felipe Franco , Hamid Kachkachi

The effects of spin-orbit coupling on the two-electron spectra in lateral coupled quantum dots are investigated analytically and numerically. It is demonstrated that in the absence of magnetic field the exchange interaction is practically…

Mesoscale and Nanoscale Physics · Physics 2010-04-12 Fabio Baruffa , Peter Stano , Jaroslav Fabian

We present a new mechanism for a spin blockade effect associated with a change in the type of magnetic anisotropy over oxidation state in a single molecule transistor, by taking an example of an individual Eu$_{2}$(C$_{8}$H$_{8}$)$_{3}$…

Mesoscale and Nanoscale Physics · Physics 2016-11-23 Guangpu Luo , Kyungwha Park

The low energy excitation spectrum of a two-dimensional ferromagnetic material is dominated by single-magnon excitations that show a gapless parabolic dispersion relation with the spin wave vector. This occurs as long as magnetic anisotropy…

Mesoscale and Nanoscale Physics · Physics 2023-10-25 F. Delgado , M. M. Otrokov , A. Arnau

An attractive feature of magnetic adatoms and molecules for nanoscale applications is their superparamagnetism, the preferred alignment of their spin along an easy axis preventing undesired spin reversal. The underlying magnetic anisotropy…

Mesoscale and Nanoscale Physics · Physics 2014-07-22 Maciej Misiorny , Michael Hell , Maarten R. Wegewijs
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