A perpendicular field electromagnet with a 250mm access bore

TL;DR

This paper introduces a laboratory electromagnet with a large access bore capable of generating up to ±0.48T, featuring high uniformity, efficient thermal dissipation, and precise temperature control for thin film experiments.

Contribution

The design of a high-field electromagnet with a large access bore, improved field uniformity, and integrated thermal regulation for experimental applications.

Findings

Magnet achieves up to ±0.48T magnetic field.

Field uniformity within ±1.5mT over 28mm² zone.

Thermal dissipation is less than 1kW at maximum field.

Abstract

We present a laboratory electromagnet capable of generating magnetic fields up to $\pm$0.48T, specifically designed as a perpendicular flux source for thin film samples in an ambient environment. The magnet features a 250mm diameter clear access bore above the sample plane, thus offering compatibility with a wide variety of experimental apparatus. Despite its generous size, the magnet thermally dissipates less than 1kW at maximum field. A shaped ferromagnetic core is used to amplify and homogenize the field $\mathbf{B}$, leading to an estimated uniformity of $\pm$1.5mT ($\lesssim$0.3%) in $\left|\mathbf{B}\right|$ within a 28mm$^2$ zone at maximum field. The sample stage is thermally regulated and isolated from the magnet, enabling temperature control with $\pm$5mK precision even at elevated magnetic fields.