Hybrid spintronic materials: Growth, structure and properties

Abstract

Spintronics is an emergent interdisciplinary topic for the studies of spin-based, other than or in addition to charge-only-based physical phenomena. Since the discovery of giant magnetoresistance (GMR) effect in metallic multilayers, the first-generation spintronics has generated huge impact to the mass data storage industries. The second-generation spintronics, on the other hand, focuses on the integration of the magnetic and semiconductor materials and so to add new capabilities to the electronic devices. While spin phenomena have long been investigated within the context of conventional ferromagnetic materials, the study of spin generation, relaxation, and spin-orbit coupling in non-magnetic materials took off only recently with the advent of hybrid spintronics and it is here many novel materials and architectures can find their greatest potentials in both science and technology. This article reviews recent progress of the research on a selection of hybrid spintronic systems including those based on ferromagnetic metal (FM) and alloys, half-metallic materials, and twodimensional (2D) materials. FM and alloys have spontaneous magnetization and usually high Curie temperature (Tc), half-metallic materials possess high spin polarization near the Fermi level (EF), and the 2D materials have unique band structures such as the Fermi Dirac cone and valley degree of freedom of the charge carriers. Enormous progress has been achieved in terms of synthesising the epitaxial hybrid spintronic materials and revealing their new structures and properties emerging from the atomic dimensions and the hetero-interfaces. Apart from the group-IV, III-V, and II-VI semiconductors and their nanostructures, spin injection and detection with 2D materials such as graphene, transition-metal dichalcogenides (TMDs) and topological insulators (TIs) has become a new trend and a particularly interesting topic due to either the long spin lifetime or strong spin-orbit coupling induced spinmomentum locking, which potentially leads to dissipationless electronic transport.

Coexisting structural phases in the catalytically driven growth of rock salt GdN

“…The last decade has seen an enormous expansion in studies of intrinsic ferromagnetic semiconductors, either 2D dimensional materials or thin films, which has opened a powerful new perspective in materials science and spintronics applications [1][2][3][4][5]. Within this scenario the fourteen mononitrides of the rare-earth (RENs) are of special interest as they are to date the only known series of intrinsic ferromagnetic semiconductors [1].…”

Spintronic devices: a promising alternative to CMOS devices

“…However, further scaling is becoming extremely difficult as the transistor size reaches few atomic layers, and the quantum effect starts to kicks-in [4]. This can lead to an increased leakage current due to the quantum tunneling and thereby increases the standby power dissipation [5][6][7]. This is a serious concern, especially in volatile memory, because we have to constantly supply power to retain the information stored in it.…”

Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics?

“…Two impactful areas aligning with these renewed mindsets are spintronics and two-dimensional (2D) materials. 1 Spintronics (Nobel Prize in Physics, 2007) offers new approaches to achieving improved device performance via the manipulation and read-out of charge carrier spin, [2][3][4][5] while 2D materials (a field launched with the isolation of graphene, Nobel Prize in Physics, 2010) offer an exceptionally wide range of exotic material properties and physical phenomena not previously accessible with conventional 3D semiconductors. [6][7][8] A strong synergy between these two fields has been developed over the last couple of years, giving birth to a new field now referred to as 2D spintronics (Figure 1).…”