The uniqueness of the driven $\varphi_0$ Josephson junction: when steps are not Shapiro

TL;DR

This paper explores the unique locking phenomena in the $\

Contribution

It introduces the concept of Buzdin steps in $\

Findings

Buzdin steps differ from Shapiro steps in origin and properties.

The width of Buzdin steps oscillates with magnetic amplitude and shows anomalies.

Analytical results show Buzdin step width as a product of two Bessel functions.

Abstract

The $\varphi_0$ superconductor-ferromagnet-superconductor Josephson junction exhibits unique locking phenomena under the external periodic signal when the magnetic component is taken into account. Contrary to the well-known Shapiro steps that come from the locking with the electric component, locking of the Josephson oscillations with the magnetic one results in the appearance of Buzdin steps in the current-voltage characteristic and a much more complex response of the system. These steps possess distinctive properties that are indications of their unique origins and locking mechanisms. The width of the Buzdin step oscillates with the amplitude of the magnetic component, nevertheless, it exhibits anomalies in the Bessel-like behavior. In addition, we perform an analytical analysis that supports the numerical results and shows that the width of the Buzdin step represents a product of two Bessel functions. Investigation of the effects that simultaneously appear in the magnetic subsystem reveals the presence of destructive interference and magnetization reorientation that accompany the appearance of Buzdin steps.