Macroscopic Quantum Coherence in Antiferromagnetic Molecular Magnets

Abstract

The macroscopic quantum coherence in a biaxial antiferromagnetic molecular magnet in the presence of magnetic field acting parallel to its hard anisotropy axis is studied within the two-sublattice model. On the basis of instanton technique in the spin-coherent-state path-integral representation, both the rigorous Wentzel-Kramers-Brillouin exponent and preexponential factor for the groundstate tunnel splitting are obtained. We find that the quantum fluctuations around the classical paths can not only induce a new quantum phase previously reported by Chiolero and Loss (Phys. Rev. Lett. 80, 169 (1998)) , but also have great influnence on the intensity of the ground-state tunnel splitting. Those features clearly have no analogue in the ferromagnetic molecular magnets. We suggest that they may be the universal behaviors in all antiferromagnetic molecular magnets. The analytical results are complemented by exact diagonalization calculation.

Classical and Quantum Magnetization Reversal Studied in Nanometer‐Sized Particles and Clusters

“…[150] Some extensions or alternative explications of Garg's result can be found in Refs. [151,152,153,154]. The period of oscillation is given by [128]:…”

Tunable optical Aharonov-Bohm effect in a semiconductor quantum ring

“…in a quantum ring (type-I quantum dot). This has spurred a considerable search and study of the optical AB effect of neutral excitons in semiconductor quantum rings by both theoretical [3][4][5][6][7][8][9] and experimental 1,12 groups.…”

Nonlinear optical properties in a nanoring: quantum size and magnetic field effect

“…With the advance of lithography and semiconductor growth techniques, the nanoring-like devices [5][6][7][8] have been realized experimentally. Due to unique character of the nanoring, the self-assembled quantum ring has become the best ideal candidate to observe Aharonov-Bohm (A-B) oscillation [9][10][11].…”

“…Over the last decade, some researchers had paid their attention to A-B effect of neutral exciton in two-dimensional quantum ring. For instance, Hu et al [9] theoretically studied the magnetic field effects on exciton in an InAs nanoring, They found that the A-B effect of exciton only exists in a finite (but small) width nanoring in the presence of Coulomb correlation. Ribeiro et al [14] experimentally presented a magneto-photoluminescence study of type-II InP/GaAs self-assembled quantum dot, which revealed that A-B type oscillations for neutral excitons when angular momentum of hole ground state ranges from l h = 0 to l h = 1, 2, and 3.…”