Substrate-Controlled Magnetism: Fe Nanowires on Vicinal Cu Surfaces.

D Hashemi,V S Stepanyuk,J Kieffer,W Hergert,M J Waters

doi:10.3390/nano10010159

Abstract

Here, we present a novel approach to controlling magnetic interactions between atomic-scale nanowires. Our ab initio calculations demonstrate the possibility to tune magnetic properties of Fe nanowires formed on vicinal Cu surfaces. Both intrawire and interwire magnetic exchange parameters are extracted from density functional theory (DFT) calculations. This study suggests that the effective interwire magnetic exchange parameters exhibit Ruderman–Kittel–Kasuya–Yosida-like (RKKY) oscillations as a function of Fe interwire separation. The choice of the vicinal Cu surface offers possibilities for controlling the magnetic coupling. Furthermore, an anisotropic Heisenberg model was used in Monte Carlo simulations to examine the stability of these magnetic configurations at finite temperatures. The predicted critical temperatures of the Fe nanowires on Cu(422) and Cu(533) surfaces are well above room temperature.

Highlights

The continued need for increasing the information storage content of high-density magnetic recording devices requires the development of new nanostructured magnetic materials such as chains—one-dimensional (1D) periodic linear arrangements of atoms
It is known that surface-state electrons on the (111) surfaces of noble metals create two-dimensional (2D) nearly free electron gases which are confined to top layers at the surfaces
Electrons in these states move along the surface, causing scattering of the surface electrons by nanostructures formed on the surface. This scattering leads to quantum interference patterns in the local density of states (LDOS) and long-range oscillatory interactions between adsorbates [29]

Summary

Introduction

The continued need for increasing the information storage content of high-density magnetic recording devices requires the development of new nanostructured magnetic materials such as chains—one-dimensional (1D) periodic linear arrangements of atoms. Most of the experimental methods and potential industrial applications require a high packing density of these chains. Cu surfaces can be prepared with a large number of atom-high steps through a procedure known as step decoration. In this process, the material is deposited on a stepped surface and subsequently nucleates along the edges of the steps with chains or nanostripes growing on the lower terraces along ascending step edges. Shen et al [1,2] demonstrated that Fe nanostripes grow on the upper terraces of stepped Cu(111) surfaces

Methods

Results

Conclusion