Single-domain versus two-domain configuration in thin ferromagnetic prisms

TL;DR

This paper investigates the transition from single-domain to two-domain states in thin ferromagnetic prisms, analyzing how the aspect ratio and physical parameters influence this transition using both discrete and continuum models.

Contribution

It provides a comparative analysis of the transition in ferromagnetic prisms using two different modeling approaches and relates findings to experimental observations.

Findings

Thicker films can undergo the single- to two-domain transition.

The critical aspect ratio p_c depends on physical parameters.

Good agreement with experimental Magnetic Force Microscopy data.

Abstract

Thin ferromagnetic elements in the form of rectangular prisms are theoretically investigated in order to study the transition from single-domain to two-domain state, with changing the in-plane aspect ratio p. We address two main questions: first, how general is the transition; second, how the critical value p_c depends on the physical parameters. We use two complementary methods: discrete-lattice calculations and a micromagnetic continuum approach. Ultrathin films do not appear to split in two domains. Instead, thicker films may undergo the above transition. We have used the continuum approach to analyze recent Magnetic Force Microscopy observations in 30 nm-thick patterned Permalloy elements, finding a good agreement for p_c.