Resonant quantum coherence of magnetization at excited states in nanospin systems with different crystal symmetries |
| |
Authors: | Jia-Lin Zhu Rong Lü Su-Peng Kou Hui Hu Bing-Lin Gu |
| |
Institution: | (1) Center for Advanced Study, Tsinghua University, Beijing 100084, PR China, CN;(2) Department of Physics, Tsinghua University, Beijing 100084, PR China, CN |
| |
Abstract: | The quantum interference effects induced by the Wess-Zumino term, or Berry phase are studied theoretically in resonant quantum
coherence of the magnetization vector between degenerate states in nanometer-scale single-domain ferromagnets in the absence
of an external magnetic field. We consider the magnetocrystalline anisotropy with trigonal, tetragonal and hexagonal crystal
symmetry, respectively. By applying the periodic instanton method in the spin-coherent-state path integral, we evaluate the
low-lying tunnel splittings between degenerate excited states of neighboring wells. And the low-lying energy level spectrum
of mth excited state are obtained with the help of the Bloch theorem in one-dimensional periodic potential. The energy level spectrum
and the thermodynamic properties of magnetic tunneling states are found to depend significantly on the total spins of ferromagnets
at sufficiently low temperatures. Possible relevance to experiments is also discussed.
Received 15 December 1999 |
| |
Keywords: | PACS 75 45 +j Macroscopic quantum phenomena in magnetic systems - 75 10 Jm Quantized spin models - 03 65 Bz Foundations theory of measurement miscellaneous theories (including Aharonov-Bohm effect Bell inequalities Berry's phase) |
本文献已被 SpringerLink 等数据库收录! |
|