Highly sensitive detection and stochastic analysis of magnetization agitation induced in a single layered magnetic wire

This study shows that broadband magnetic noise in a ferromagnetic wire can be detected over a wide frequency range between 500 MHz and 8 GHz using a lock-in detection technique. The magnetic noise spectrum from a 20 nm-thick single-layered Fe19Ni81 wire biased with a dc current is measured as functions of an external field and dc current. This noise is caused by thermal agitation in magnetization due to ambient temperature and Joule heating. The noise behaviors are well reproduced by a stochastic model. Thus, this paper presents a stochastic analysis of magnetic noise behaviors induced by thermal agitation using a highly sensitive technique for detecting the magnetic noise in a single layered ferromagnetic wire.