Origin of Magnetism in γ-FeSi2/Si(111) Nanostructures.

Liwei D Geng,Yongmei M Jin,Sahil Dhoka,Ilan Goldfarb,Ranjit Pati

doi:10.3390/nano11040849

Liwei D Geng, Yongmei M Jin + Show 3 more

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https://doi.org/10.3390/nano11040849

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Abstract

Magnetism has recently been observed in nominally nonmagnetic iron disilicide in the form of epitaxial γ-FeSi2 nanostructures on Si(111) substrate. To explore the origin of the magnetism in γ-FeSi2/Si(111) nanostructures, we performed a systematic first-principles study based on density functional theory. Several possible factors, such as epitaxial strain, free surface, interface, and edge, were examined. The calculations show that among these factors, only the edge can lead to the magnetism in γ-FeSi2/Si(111) nanostructures. It is shown that magnetism exhibits a strong dependency on the local atomic structure of the edge. Furthermore, magnetism can be enhanced by creating multiple-step edges. In addition, the results also reveal that edge orientation can have a significant effect on magnetism. These findings, thus, provide insights into a strategy to tune the magnetic properties of γ-FeSi2/Si(111) nanostructures through controlling the structure, population, and orientation of the edges.

Highlights

Transition-metal silicides are important technological materials because of their advantageous properties, such as good electrical conductivity, thermal stability, and high chemical inertness [1,2,3,4]
We examined several factors that could contribute to the magnetism in nanostructures, such as the epitaxial strain, free surface, interface, and edge
Regarding the specific geometry of the γ-FeSi2 /Si(111) nanostructures, several factors could contribute to magnetism, including epitaxial strain, free surface, interface, and edge

Summary

Introduction

Transition-metal silicides are important technological materials because of their advantageous properties, such as good electrical conductivity, thermal stability, and high chemical inertness [1,2,3,4]. Since Si is diamagnetic, a vast majority of bulk transition-metal silicides are nonmagnetic. Most bulk-size silicide crystals, based on the three typical transitional elements (Fe, Co, Ni), are reported to be nonmagnetic except for Fe-rich Fe3 Si and Fe5 Si3 [5,6,7,8]. Epitaxial transition-metal silicide nanostructures often exhibit unique magnetic properties that are not present in their bulk constituents and, have been the subject of intense research because of their technological potential in Si-based technology for spintronics devices [9,10,11,12]. In transition-metal silicide nanostructures, even Si-rich silicides can exhibit ferromagnetic ordering. A ferromagnetic response has been observed for iron disilicide

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