Exact cloaking of uniform magnetic fields with a superconductor-magnetic bilayer

TL;DR

This paper analytically demonstrates that a bilayer of a superconductor and a magnetic material can achieve exact cloaking of uniform magnetic fields, overcoming previous material limitations for electromagnetic cloaking.

Contribution

It introduces a simple concentric bilayer design with homogeneous, isotropic layers for exact magnetic cloaking of uniform fields, a significant advancement over complex previous schemes.

Findings

The bilayer maintains an unperturbed external magnetic field.

Superconducting inner layer prevents external fields from entering.

Cloaking effectiveness can be optimized for inhomogeneous fields.

Abstract

The experimental realization of cloaks for electromagnetic fields has been possible only in reduced schemes because of extreme material conditions required in exact cloaks. Here we analytically demonstrate that a simple arrangement of two concentric homogeneous and isotropic layers with different permeabilities can keep a uniform externally applied magnetic field unperturbed. If the inner layer is superconducting, the device prevents exterior fields from entering an enclosed region, which represents a case for an exact cloaking of uniform fields. When the applied field is inhomogeneous the cloaking property is reduced but may be optimized by changing the thickness of the layers.