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Escape rate of the nanospin system in a magnetic field: the first-order phase transition within quantum regime

Chang Soo Park·Sahng-Kyoon Yoo·D. K. Park·Dal-Ho Yoon
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Abstract

We have investigated the escape rate of the nanospin particle with a magnetic field applied along the easy axis. The model studied here is described by the Hamiltonian $\hat{\cal H} = K_1 \hat{S}_z^2 + K_2 \hat{S}_y^2 + gμ_b H \hat{S}_x $, $(K_1 > K_2 > 0)$ from which the escape rate is calculated within the semiclassical approximation. We have obtained a diagram for the orders of the phase transitions depending on the anisotropy constant and the external field. For $ K_2 / K_1 > 0.85$ the present model reveals, for the first time, the existence of the first-order transition within the quantum regime.

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Chang Soo Park, Sahng-Kyoon Yoo, D. K. Park, Dal-Ho Yoon. 1998-07-26. Escape rate of the nanospin system in a magnetic field: the first-order phase transition within quantum regime. https://arxiv.org/abs/cond-mat/9807344

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