Change in the magnetic configurations of tubular nanostructures by tuning dipolar interactions

ABSTRACT: We have investigated the equilibrium states of ferromagnetic single wall nanotubes by means of atomistic Monte Carlo simulations of a zig-zag lattice of Heisenberg spins on the surface of a cylinder. The main focus of our study is to determine how the competition between short-range exchange (J) and long-range dipolar (D) interactions infuences the low temperature magnetic order of the nanotubes as well as the thermal-driven transitions involved. Apart from the uniform and vortex states occurring for dominant J or D, we fnd that helical states become stable for a range of intermediate values of γ=D/J that depends on the radius and length of the nanotube. Introducing a vorticity order parameter to better characterize helical and vortex states, we fnd the pseudo-critical temperatures for the transitions between these states and we establish the magnetic phase diagrams of their stability regions as a function of the nanotube aspect ratio. Comparison of the energy of the states obtained by simulation with those of simpler theoretical structures that interpolate continuously between them, reveals a high degree of metastability of the helical structures that might be relevant for their reversal modes.

• Autores: Salinas Jiménez, Hernán David; Restrepo Cárdenas, Johans; Iglesias, Óscar
• Tipo de recurso: Article of investigation
• Fecha de publicación: 2018
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/40133
• Acceso en línea: https://hdl.handle.net/10495/40133
• Palabra clave: Nanotubos; Nanotubes; Nanoestructuras; Nanostructures; Método de Montecarlo; Monte carlo method; https://id.nlm.nih.gov/mesh/D043942; https://id.nlm.nih.gov/mesh/D049329
• Rights: openAccess
• License: http://creativecommons.org/licenses/by/2.5/co/