Macroscopic Quantum Coherence in Small Antiferromagnetic Particle and the Quantum Interference Effects

  • Starting from the Hamiltonian operator of the noncompensated two-sublattice model of a small antiferromagnetic particle, we derive the e effective Lagrangian of a biaxial antiferromagnetic particle in an external magnetic field with the help of spin-coherent-state path integrals. Two unequal level-shifts induced by tunneling through two types of barriers are obtained using the instanton method. The energy spectrum is found from Bloch theory regarding the periodic potential as a superlattice. The external magnetic field indeed removes Kramers' degeneracy, however a new quenching of the energy splitting depending on the applied magnetic field is observed for both integer and half-integer spins due to the quantum interference between transitions through two types of barriers.

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Author:Yi-Hang Nie, Y.-B. Zhang, J.-Q. Liang, H.J.W. Müller-Kirsten, F.-C. Pu
URN (permanent link):urn:nbn:de:hbz:386-kluedo-10960
Document Type:Preprint
Language of publication:English
Year of Completion:1999
Year of Publication:1999
Publishing Institute:Technische Universität Kaiserslautern
Tag:instanton method ; level splitting; macroscopic quantum coherence
Faculties / Organisational entities:Fachbereich Physik
DDC-Cassification:530 Physik

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