Related papers: Destructive quantum interference in spin tunneling…
The collective tunneling of a small cluster of spins between two degenerate ground state configurations of the Kagom\'{e}-lattice quantum Heisenberg antiferromagnet is \mbox{studied}. The cluster consists of the six spins on a hexagon of…
The quantum interference effects induced by the topological phase are studied analytically in biaxial antiferromagnets with an external magnetic field at an arbitrarily angle. This study provides a nontrivial generalization of the Kramers…
Within a wide class of ferromagnetic and antiferromagnetic systems, quantum tunneling of magnetization direction is spin-parity dependent: it vanishes for magnetic particles with half-integer spin, but is allowed for integer spin. A…
The spin-phase interference effects are studied analytically in resonant quantum tunneling of the N\'{e}el vector between degenerate excited levels in nanometer-scale single-domain antiferromagnets in the absence of an external magnetic…
We theoretically investigate transport signatures of quantum interference in highly symmetric double quantum dots in a parallel geometry and demonstrate that extremely weak symmetry-breaking effects can have a dramatic influence on the…
The point-particle-like Hamiltonian of a biaxial spin particle with external magnetic field along the hard axis is obtained in terms of the potential field description of spin systems with exact spin-coordinate correspondence. The Zeeman…
Macroscopic quantum coherence and spin-phase interference are studied between excited levels in single-domain ferromagnetic particles in a magnetic field along the hard anisotropy axis. The system has the general structure of…
Magnetization measurements of Mn12 molecular nanomagnets with spin ground states of S = 10 and S = 19/2 showresonance tunneling at avoided energy level crossings. The observed oscillations of the tunnel probability as a function of the…
We present an exact analytic study on the topological phase interference effect in resonant quantum tunneling of the magnetization between degenerate excited levels for biaxial ferromagnets in an arbitrarily directed magnetic field. We show…
The interplay between classical chaos and quantum tunneling is examined in driven nonlinear systems, with emphasis on how semi classical phase space structures influence purely quantum transport phenomena. We show that, in the presence of…
We analyze dephasing in a model system where electrons tunnel sequentially through a symmetric interference setup consisting of two single-level quantum dots. Depending on the phase difference between the two tunneling paths, this may…
Theoretical foundations of the problem of quantum spin tunneling in magnetic nanostructures are presented. Several model problems are considered in detail, including recent new results on tunneling in antiferromagnetic nanoparticles and…
We analyze the interference between tunneling paths that occurs for a spin system with both fourth-order and second-order transverse anisotropy. Using an instanton approach, we find that as the strength of the second-order transverse…
We study quantum interference effects due to electron motion on the Kagom\'e lattice in a perpendicular magnetic field. These effects arise from the interference between phase factors associated with different electron closed-paths. From…
We study quantum interference effects due to electron motion on a three-dimensional cubic lattice in a continuously-tunable magnetic field of arbitrary orientation and magnitude. These effects arise from the interference between magnetic…
For a two-sublattice antiferromagnet the Lagrangian is constructed taking into account Berry phase whose form is matched to the quantum-mechanical Heisenberg Hamiltonian. Tunnel effects are analyzed taking into account the crystallographic…
This article presents a review on the theoretical and the experimental developments on macroscopic quantum tunneling and phase transition of the escape rate in spin systems. We present the basic ideas with simplified calculations so that it…
We consider a phase-coherent system of two parallel quantum wires that are coupled via a tunneling barrier of finite length. The usual perturbative treatment of tunneling fails in this case, even in the diffusive limit, once the length L of…
We present topological interference effects for the tunneling of a single large spin, which are caused by the symmetry of a general class of magnetic anisotropies. The interference originates from spin Berry phases associated with different…
The theory for the quantum tunneling of nano-magnets is developed within the intermediate spin framework. Periodic magnetic effects are seen to reflect that associated with a change of flux by a single flux quantum $\Phi_{0}$. Essential are…