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

Y. -H. Nie·Y. -B. Zhang·J. -Q. Liang·H. J. W. Mueller-Kirsten·F. -C. Pu
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Abstract

Starting from the Hamiltonian operator of the noncompensated two-sublattice model of a small antiferromagnetic particle, we derive the 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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Y. -H. Nie, Y. -B. Zhang, J. -Q. Liang, H. J. W. Mueller-Kirsten, F. -C. Pu. 1999-09-27. Macroscopic Quantum Coherence in Small Antiferromagnetic Particle and the Quantum Interference Effects. https://doi.org/10.1016/s0921-4526(99)00161-1

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