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Spin tunneling of trigonal and hexagonal ferromagnets in an arbitrarily directed magnetic field

Rong Lu·Jia-Lin Zhu·Zhi-Rong Liu·Lee Chang·Bing-Lin Gu
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Abstract

The quantum tunneling of the magnetization vector are studied theoretically in single-domain ferromagnetic nanoparticles placed in an external magnetic field at an arbitrarily directed angle in the $ZX$ plane. We consider the magnetocrystalline anisotropy with trigonal and hexagonal crystal symmetry, respectively. By applying the instanton technique in the spin-coherent-state path-integral representation, we calculate the tunnel splittings, the tunneling rates and the crossover temperatures in the low barrier limit for different angle ranges of the external magnetic field ($θ_{H}=π/2$, $π/2\llθ_{H}\llπ$, and $θ_{H}=π$). Our results show that the tunnel splittings, the tunneling rates and the crossover temperatures depend on the orientation of the external magnetic field distinctly, which provides a possible experimental test for magnetic quantum tunneling in nanometer-scale single-domain ferromagnets.

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Rong Lu, Jia-Lin Zhu, Zhi-Rong Liu, Lee Chang, Bing-Lin Gu. 2000-05-23. Spin tunneling of trigonal and hexagonal ferromagnets in an arbitrarily directed magnetic field. https://doi.org/10.1088/0953-8984%2F12%2F20%2F306

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