Limit cycle induced frequency locking in self-sustained current oscillations of superlattices

TL;DR

This paper investigates how self-sustained current oscillations in superlattices lock their frequency to external signals through limit cycle deformation, supported by numerical and experimental evidence within nonlinear physics.

Contribution

It introduces a new understanding of frequency locking in superlattices via limit cycle deformation, combining theoretical, numerical, and experimental approaches.

Findings

Frequency locking occurs at integer fractions of the ac frequency.

Limit cycles can deform with or without topological change during locking.

The phenomenon is robust against variations in ac bias.

Abstract

The ac response of self-sustained current oscillations (SSCOs) in GaAs/AlAs superlattices (SLs) is derived based on the deformation of a limit cycle under an external ac driving force. Frequency locking into an integer fraction of the ac frequency is obtained in a periodic response in which a limit cycle deforms either with or without a topological change. This frequency locking is robust against the ac bias because a limit cycle can adjust itself. The results are verified both numerically and experimentally, indicating that SSCOs in SLs can be understood within the framework of the general concepts and principles of nonlinear physics.