Tunneling and inversion symmetry in single-molecule magnets: the case of the Mn12 wheel molecule
arXiv:1007.0949 · doi:10.1103/PhysRevB.82.104426
Abstract
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 roles played by secondary influences, e.g. disorder, dipolar and hyperfine fields, and magnetoacoustic interactions. Special attention is paid to the role of the antisymmetric Dzyaloshinski-Moriya (DM) interaction. This is done within the framework of a 12-spin microscopic model, and also using simplified dimer and tetramer approximations in which the electronic spins are grouped in 2 or 4 blocks, respectively. If the molecule is inversion symmetric, the DM interaction between the dimer halves must be zero. In an inversion symmetric tetramer, two independent DM vectors are allowed, but no new tunneling transitions are generated by the DM interaction. Experiments on the Mn12 wheel can only be explained if the molecular inversion symmetry is broken, and we explore this in detail using both models, focussing on the asymmetric disposition and rounding of Berry phase minima associated with quantum interference between states of opposite parity. A remarkable behavior exists for the `Berry phase zeroes' as a function of the directions of the internal DM vectors and the external transverse field. A rather drastic breaking of the molecular inversion-symmetry is required to explain the experiments; in the tetramer model this requires a reorientation of the DM vectors on one half of the molecule by nearly 180 degrees. This cannot be attributed to sample disorder. These results are of general interest for the quantum dynamics of tunneling spins, and lead to some interesting experimental predictions.
arXiv commentSubmitted to PRB. 23 double-column pages, 16 figures
References in corpus (47)
- Theory of the spin bath
- Suppression of tunneling by interference in half-integer--spin particles
- Low-Temperature Quantum Relaxation in a System of Magnetic Nanomolecules
- Destructive quantum interference in spin tunneling problems
- Symmetry breaking due to Dzyaloshinsky-Moriya interactions in the kagome lattice
- Observation of the distribution of molecular spin states by resonant quantum tunneling of the magnetization
- Anisotropic Spin Hamiltonians due to Spin-Orbit and Coulomb Exchange Interactions
- The effects of nuclear spins on the quantum relaxation of the magnetization for the molecular nanomagnet Fe_8
- The origin of second-order transverse magnetic anisotropy in Mn12-acetate
- Magnetic Quantum Tunneling: Insights from Simple Molecule-Based Magnets
- Quantum Relaxation of Magnetisation in Magnetic Particles
- Tunable Quantum Tunneling of Magnetic Domain Walls
- Quantum Phase Transition of a Magnet in a Spin Bath
- Effects of D-strain, g-strain, and dipolar interactions on EPR linewidths of the molecular magnets Fe8 and Mn12
- Definitive spectroscopic determination of the transverse interactions responsible for the magnetic quantum tunneling in Mn12-acetate
- Macroscopic Quantum Tunneling of a Domain Wall in a Ferromagnetic Metal
- Pair-wise decoherence in coupled spin qubit networks
- Propagation of Avalanches in Mn-acetate: Magnetic Deflagration
- Stability of Bose Einstein condensates of hot magnons in YIG
- Spin relaxation in Mn12-acetate
- Quantum nucleation in a single-chain magnet
- Symmetry of Magnetic Quantum Tunneling in Single Molecule Magnet Mn12-acetate
- A Distribution of Tunnel Splittings in Mn-Acetate
- Quantum and Classical Glass Transitions in
- Quantum Magnetic Deflagration in Mn12 Acetate
- Observation of Spin Glass Dynamics in Dilute LiHoYF
- Magnetic long-range order induced by quantum relaxation in single-molecule magnets
- Fast quantum noise in Landau-Zener transition
- Significance of the Hyperfine Interactions in the Phase Diagram of
- Long-range ferromagnetic dipolar ordering of high-spin molecular clusters
- Absence of Conventional Spin-Glass Transition in the Ising Dipolar System LiHo_xY_{1-x}F_4
- Theory of Anisotropic Superexchange in Insulating Cuprates
- Nuclear spin dynamics in the quantum regime of a single-molecule magnet
- Quantum Step Heights in Hysteresis Loops of Molecular Magnets
- 55Mn NMR in Mn12 acetate: Hyperfine interaction and magnetic relaxation of cluster
- Strongly Correlated Electrons in the Single Molecule Magnet: A DFT+U Study
- Influence of the Dzyaloshinskii-Moriya exchange interaction on quantum phase interference of spins
- Role of anisotropy in the spin-dimer compound BaCuSi2O6
- Direct observation of mixing of spin-multiplets in an antiferromagnetic molecular nanomagnet by electron paramagnetic resonance
- Realization of random-field dipolar Ising ferromagnetism in a molecular magnet
- 'Hole-digging' in ensembles of tunneling Molecular Magnets
- Many-body Landau-Zener effect at fast sweep
- Influence of antisymmetric exchange interaction on quantum tunneling of magnetization in a dimeric molecular magnet Mn6
- Dynamics and thermalization of the nuclear spin bath in the single-molecule magnet Mn12-ac: test for the theory of spin tunneling
- Pure and Random-Field Quantum Criticality in the Dipolar Ising Model: Theory of acetates
- Incoherent Landau-Zener-Stuckelberg Transitions in Single-Molecule Magnets
- Comment on "Influence of Dzyaloshinskii-Moriya Exchange Interaction on Quantum Phase Interference of Spins"
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- Effects of uniaxial pressure on the quantum tunneling of magnetization in a high-symmetry Mn12 single-molecule magnet
- Thermodynamics of a Quantum Ising system coupled to a spin bath: Zero Temperature Results