Double tunneling in polarization switching

摘要

We present a theory of quantum switching of polarization in hydrogen-bonded order_Cdisorderferroelectrics, and examine the macroscopic quantum-tunneling rate of the polarization reversal fornano-samples induced by microscopic tunneling of protons between the two wells in potentials ofhydrogen bonds. We compute the rate of the electric polarization tunneling through the barrier betweentwo minima of the free energy density of a system. By using the instanton approach, we calculate abarrier factor and a prefactor multiplying the exponential of the action integral for the tunneling splittingat zero applied electric field. We compute the tunneling rate of domain walls. We obtain the doubletunneling effect, i.e., the polarization tunneling related to the proton tunneling between the two minimain potentials of hydrogen bonds.