Magnetic and structural properties of Py thin films deposited in substrates with periodic roughness

M. ARANA; P. G. BERCOFF

Encuentro; Encuentro de otoño de la Sociedad Brasilera de Física; 2023

Thin films of Ni-Fe of Ni0,81Fe0,19 stoichiometry, known as permalloy (Py), are of special interest in information technologies (IT) due to their unique features. Among them, a high saturation magnetization, a strong dependence on coercivity with thickness, and stable ferromagnetic properties at room temperature are highlighted [1]. In spintronics experiments, Py is used in Py/M bilayers as an injector font of spin current [2] in materials M with high spin Hall angles as Pt [3]. Besides, Py is usually used as a seed layer, as the first layer of a multilayer sample, to fix the magnetization direction. Py has its main applications in ferromagnet/antiferromagnet (FM/AFM) bilayers for studying the exchange bias effect and in multilayers [4] for studying the magnetoresistance phenomenon. In several works, Py is deposited in pure Si (111) substrates or oxidized Si with a thin layer of SiO2, showing high crystallinity and good adherence without needing to add a buffer layer. Those features make Py versatile in several applications. In particular, Py has surface magnetic texture, a property that determines that this compound is a good candidate to prepare thin films with some anisotropy degree. Recently, authors report skyrmion formation when magnetic materials are deposited on the surface of rough substrates [5], making this kind of nanostructure of special interest for preparing nanodomes, which application in IT is the magnetic recording of high-density data. In this work, we present the morphological characteristics, and the structural and magnetic properties of Py thin films of different thickness when deposited in smooth substrates, in comparison with the properties when the films are deposited in substrates with ridges and valleys. In the latter, in both cases, the used substrates are membranes with a high degree of periodic order, giving periodic roughness at the film surface, that is, more surface anisotropy.[1] M. Arana, M. Gamino, A. B. Oliveira, J. Holanda, A. Azevedo, S. M. Rezende, and R. L. Rodríguez-Suárez. Phys. Rev. B 102 (2020)104405[2] J. Holanda, O. Alves Santos, R. O. Cunha, J. B. S. Mendes, R. L. Rodríguez-Suárez, A. Azevedo, and S. M. Rezende. Phys. Rev. B 95 (2017) 214421[3] A. Azevedo, R. O. Cunha, F. Estrada, O. Alves Santos, J. B. S. Mendes, L. H. Vilela-Leão, R. L. Rodríguez-Suárez, and S. M. Rezende. Phys. Rev. B 92 (2015) 024402-1[4] M. Arana, M. Gamino, A. B. Oliveira, J. Holanda, A. Azevedo, S. M. Rezende, and R. L. Rodríguez-Suárez. Phys. Rev. B 102 (2020)104405.[5] Stabilization of Magnetic Skyrmions on Arrays of Self-Assembled Hexagonal Nanodomes for Magnetic Recording Applications”, F. Tejo, D. Toneto, S. Oyarzún, J. Hermosilla, C. S. Danna, J. L. Palma, R. B. da Silva, L. S. Dorneles, and J. C. Denardin. ACS Appl. Mater. Interfaces 2020, 12, 53454−53461