Quantum Tunneling between Paramagnetic and Superconducting States of a Nanometer-Scale Superconducting Grain Placed in a Magnetic Field

A. V. Lopatin; V. M. Vinokur

doi:10.1103/PhysRevLett.90.047003

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Quantum Tunneling between Paramagnetic and Superconducting States of a Nanometer-Scale Superconducting Grain Placed in a Magnetic Field

A. V. Lopatin, V. M. Vinokur

DOI 10.1103/PhysRevLett.90.047003 · Physical Review Letters

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Abstract

We consider the process of quantum tunneling between the superconducting and paramagnetic states of a nanometer-scale superconducting grain placed in a magnetic field. The grain is supposed to be weakly coupled to a normal metallic contact that plays the role of the spin reservoir. Using the instanton method, we find the probability of the quantum tunneling process and express it in terms of the applied magnetic field, order parameter of the superconducting grain, and conductance of the tunneling junction between the grain and metallic contact.