# Effect of dipolar interactions and DC magnetic field on the specific absorption rate of an array of magnetic nanoparticles

## TL;DR

This paper develops a theoretical model to analyze how dipolar interactions and DC magnetic fields influence the specific absorption rate in magnetic nanoparticle arrays, revealing conditions for optimal hyperthermia performance.

## Contribution

It introduces a new theory for calculating AC susceptibility and SAR in nanoparticle assemblies considering dipolar interactions and DC fields, including competition effects.

## Key findings

- SAR has a maximum at a critical DC field depending on particle separation.
- The critical DC field in the longitudinal configuration aligns with experimental ranges.
- Dipolar interactions can both enhance and suppress SAR depending on conditions.

## Abstract

We address the issue of inter-particle dipolar interactions in the context of magnetic hyperthermia. More precisely, the main question dealt with here is concerned with the conditions under which the specific absorption rate is enhanced or reduced by dipolar interactions. For this purpose, we propose a theory for the calculation of the AC susceptibility, and thereby the specific absorption rate, for a monodisperse two-dimensional assembly of nanoparticles with oriented anisotropy, in the presence of a DC magnetic field, in addition to the AC magnetic field. We also study the competition between the dipolar interactions and the DC field, both in the transverse and longitudinal configurations. In both cases, we find that the specific absorption rate has a maximum at some critical DC field that depends on the inter-particle separation. In the longitudinal setup, this critical field falls well within the range of experiments.