# \txtit{In situ} determination of the anisotropy field in ferromagnetic films using magnetic susceptibility measurements by MOKE

## TL;DR

This paper introduces a simple in situ method using MOKE to measure anisotropy fields in ferromagnetic thin films, suitable when traditional methods are impractical, and demonstrates its effectiveness on Co/W(110) and CoO/Co/W(110) films.

## Contribution

The paper presents a novel, accessible technique for in situ anisotropy field measurement using magnetic susceptibility via MOKE, applicable to various thin film ferromagnets.

## Key findings

- Accurate anisotropy fields obtained for Co/W(110) films.
- Detection of interfacial exchange coupling effects.
- Determination of the Néel temperature of CoO layer.

## Abstract

An alternate method of measuring anisotropy fields in thin film ferromagnets is demonstrated. The method relies on the magnetic susceptibility in a small a.c. magnetic field, measured \txtit{in situ} using the magneto-optic Kerr effect (MOKE), and will be useful in situations where more specialized apparatus are not available, or constraints discourage the use of a large, static magnetic field. The method is demonstrated for Co/W(110) films, where it yields anisotropy fields in agreement with previous studies using more conventional torque magnetometry. The sensitivity of the method is demonstrated using CoO/Co/W(110) bilayer films, where the anisotropy due to interfacial exchange coupling is detected and used to find the N\'{e}el temperature of the thin CoO layer.