Quantum Tunneling of the Magnetic Moment in the S/F/S Josephson ${\bm \varphi}_{\bf 0}$-Junction

Abstract

We show that the S/F/S Josephson $\varphi_0$-junction permits detection of macroscopic quantum tunneling and quantum oscillation of the magnetic moment by measuring the ac voltage across the junction. Exact expression for the tunnel splitting renormalized by the interaction with the superconducting order parameter is obtained. It is demonstrated that magnetic tunneling may become frozen at a sufficiently large $\varphi_0$. The quality factor of quantum oscillations of the magnetic moment due to finite Ohmic resistance of the junction is computed. It is shown that magnetic tunneling rate in the $\varphi_0$-junction can be controled by the supercurrent, with no need for the magnetic field.