Macroscopic Quantum Coherence in Antiferromagnetic Molecular
Magnets |
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Authors: | HU Hui LÜ Rong ZHU Jia-Lin XIONG Jia-Jiong |
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Institution: | 1. Department of Physics, Tsinghua University, Beijing 100084, China
;2. Center for Advanced Study, Tsinghua University, Beijing 100084, China |
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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 pre-exponential factor for the ground-state 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 (1998) 169), but also have great influence 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. |
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Keywords: | macroscopic quantum coherence two-sublattice model antiferromagnetic molecular magnets |
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