An analytical computation of magnetic field generated from a cylinder ferromagnet

TL;DR

This paper presents an analytical method to compute the magnetic field from a uniformly magnetized cylindrical ferromagnet, applicable inside and outside the magnet, aiding in the design of magnetic devices.

Contribution

It develops exact solutions for magnetic fields from a cylinder ferromagnet with arbitrary magnetization directions, validated against existing demagnetization coefficients.

Findings

Derived formulas match previous demagnetization coefficients.

Applicable to design of high-density magnetic recording devices.

Analyzed magnetic field from a spin torque oscillator.

Abstract

An analytical formulation to compute a magnetic field generated from an uniformly magnetized cylinder ferromagnet is developed. Exact solutions of the magnetic field generated from the magnetization pointing in an arbitrary direction are derived, which are applicable both inside and outside the ferromagnet. The validities of the present formulas are confirmed by comparing them with demagnetization coefficients estimated in earlier works. The results will be useful for designing practical applications, such as high-density magnetic recording and microwave generators, where nanostructured ferromagnets are coupled to each other through the dipole interactions and show cooperative phenomena such as synchronization. As an example, the magnetic field generated from a spin torque oscillator for magnetic recording based on microwave assisted magnetization reversal is studied.