Mechanical properties of macroscopic magnetocrystals

• Published in: Journal of magnetism and magnetic materials 2019-06, Vol.479, p.149-155
• Main Authors: Hidalgo-Caballero, S., Escobar-Ortega, Y.Y., Becerra-Deana, R.I., Salazar, J.M., Pacheco-Vázquez, F.
• Format: Article
• Language: English
• Subjects: Anisotropy; Bending; Bending stresses; Brittleness; Computer simulation; Condensed Matter; Crystal structure; Crystallinity; Crystallography; Deformation; Ductile-brittle transition; Embrittlement; Failure; Fracture; Hexagonal lattice; Hybrid structures; Isotropy; Magnetic crystals; Magnetic properties; Mechanical analysis; Mechanical properties; Mechanical response; Metamaterials; Physics; Statistical Mechanics; Tensile strength; Tensile stress; Torsional strength
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2019.02.031

•Magnetocrystals are brittle/ductile depending on the direction of applied stress.•Cubic magnetocrystals are ductile under tension and brittle under bending.•Hexagonal arrays are brittle under tension and ductile under bending.•Hybrid crystals combine the elasticity of cubic arrays with the strength of hexagonal arrays.•Crystalline magnetic arrays are of potential use in the design of metamaterials. We studied experimentally and by numerical simulations the mechanical response of arrays of macroscopic magnetic spheres when an external stress is applied. First, the tensile strength of single chains and ribbons was analyzed. Then, simple cubic (cP), hexagonal (Hx) and hybrid (cP-Hx) structures, called here magnetocrystals, were assembled and subjected to tensile stress, bending stress and torsion until failure was reached. Atomistic crystalline structures are isotropic, but in the case of magnetocrystals, even when geometric isotropy is obeyed, dipolar magnetic interactions introduce a physical anisotropy which modifies, in a non-usual manner, the structures response to the kind of external stress applied. For instance, cP and Hx magnetocrystals subjected to tension exhibit a behavior akin to a brittle and ductile failure, respectively, but under bending the cP structure becomes ductile while the hexagonal lattice becomes brittle. For the hybrid structure, its elastic response and strength are enhanced or reduced depending on which crystallographic direction the stress is applied. These properties, so far unexplored, give to crystalline magnetic arrays a potential interest in the design of metamaterials.