scispace - formally typeset
Search or ask a question
Topic

Half-metal

About: Half-metal is a research topic. Over the lifetime, 416 publications have been published within this topic receiving 12445 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors proposed the incorporation of half-metallic Heusler alloys grown at high temperatures (>200°C) along with insertion of a MgO tunnel barrier at the ferromagnet/semiconductor interface to minimize magnetic impurity in-diffusion and potentially act as a spin filter.
Abstract: The notion of using electron spins as bits for highly efficient computation coupled with non-volatile data storage has driven an intense international research effort over the past decade. Such an approach, known as spin-based electronics or spintronics, is considered to be a promising alternative to charge-based electronics in future integrated circuit technologies. Many proposed spin-based devices, such as the well-known spin-transistor, require injection of spin polarized currents from ferromagnetic layers into semiconductor channels, where the degree of injected spin polarization is crucial to the overall device performance. Several ferromagnetic Heusler alloys are predicted to be half-metallic, meaning 100% spin-polarized at the Fermi level, and hence considered to be excellent candidates for electrical spin injection. Furthermore, they exhibit high Curie temperatures and close lattice matching to III-V semiconductors. Despite their promise, Heusler alloy/semiconductor heterostructures investigated in the past decade have failed to fulfill the expectation of near perfect spin injection and in certain cases have even demonstrated inferior behavior compared to their elemental ferromagnetic counterparts. To address this problem, a slew of theoretical and experimental work has emerged studying Heusler alloy/semiconductor interface properties. Here, we review the dominant prohibitive materials challenges that have been identified, namely atomic disorder in the Heusler alloy and in-diffusion of magnetic impurities into the semiconductor, and their ensuing detrimental effects on spin injection. To mitigate these effects, we propose the incorporation of half-metallic Heusler alloys grown at high temperatures (>200 °C) along with insertion of a MgO tunnel barrier at the ferromagnet/semiconductor interface to minimize magnetic impurity in-diffusion and potentially act as a spin-filter. By considering evidence from a variety of structural, optical, and electrical studies, we hope to paint a realistic picture of the materials environment encountered by spins upon injection from Heusler alloys into semiconductors. Finally, we review several emerging device paradigms that utilize Heusler alloys as sources of spin polarized electrons.

129 citations

Journal ArticleDOI
TL;DR: It is shown that applying stress can alter the carrier concentration as well as mobility of the holes and electrons in the majority spin channel, thus the Curie temperature of this system can be enhanced by applying stress or doping impurities.
Abstract: We investigate the electronic structure and magnetic properties of GdN as a function of unit cell volume. Based on the first-principles calculations of GdN, we observe that there is a transformation in the conduction properties associated with the volume increase: first from half-metallic to semimetallic, then ultimately to semiconducting. We show that applying stress can alter the carrier concentration as well as mobility of the holes and electrons in the majority spin channel. In addition, we found that the exchange parameters depend strongly on lattice constant, thus the Curie temperature of this system can be enhanced by applying stress or doping impurities.

123 citations

Journal ArticleDOI
TL;DR: In this paper, the progress and issues related to integrating full and half Heusler alloys into ferromagnetic compound semiconductor heterostructures are discussed, as well as their properties.
Abstract: Ferromagnetic materials that have Curie temperatures above room temperature, crystal structures and lattice matching compatible with compound semiconductors, and high spin polarizations show great promise for integration with semiconductor spintronics. Heusler alloys have crystal structures (fcc) and lattice parameters similar to many compound semiconductors, high spin polarization at the Fermi level, and high Curie temperatures. These properties make them particularly attractive for injectors and detectors of spin-polarized currents. This review discusses the progress and issues related to integrating full and half Heusler alloys into ferromagnetic compound semiconductor heterostructures.

112 citations

Journal ArticleDOI
TL;DR: It is demonstrated that APB defects on the {110} planes are unusually stable and induce antiferromagnetic coupling between adjacent domains providing an explanation for the magnetoresistance and reduced spin polarization often observed.
Abstract: The complex and intriguing properties of the ferrimagnetic half metal magnetite (Fe3O4) are of continuing fundamental interest as well as being important for practical applications in spintronics, magnetism, catalysis and medicine. There is considerable speculation concerning the role of the ubiquitous antiphase boundary (APB) defects in magnetite, however, direct information on their structure and properties has remained challenging to obtain. Here we combine predictive first principles modelling with high-resolution transmission electron microscopy to unambiguously determine the three-dimensional structure of APBs in magnetite. We demonstrate that APB defects on the {110} planes are unusually stable and induce antiferromagnetic coupling between adjacent domains providing an explanation for the magnetoresistance and reduced spin polarization often observed. We also demonstrate how the high stability of the {110} APB defects is connected to the existence of a metastable bulk phase of Fe3O4, which could be stabilized by strain in films or nanostructures.

111 citations

Journal ArticleDOI
TL;DR: In this paper, the stable YN2 monolayer with octahedral coordination is a novel p-state Dirac half metal, which not only has a fully spin-polarized Dirac state, but also has the highest Fermi velocity (3.74 × 105 m/s) of the DHMs reported to date.
Abstract: In spintronics, it is highly desirable to find new materials that can simultaneously possess complete spin-polarization, high-speed conduction electrons, large Curie temperature, and robust ferromagnetic ground states. Using first-principles calculations, we demonstrate that the stable YN2 monolayer with octahedral coordination is a novel p-state Dirac half metal (DHM), which not only has a fully spin-polarized Dirac state, but also the highest Fermi velocity (3.74 × 105 m/s) of the DHMs reported to date. In addition, its half-metallic gap of 1.53 eV is large enough to prevent the spin-flip transition. Because of the strong nonlocal p orbitals of N atoms (N-p) direct exchange interaction, the Curie temperature reaches over 332 K. Moreover, its ferromagnetic ground state can be well preserved under carrier doping or external strain. Therefore, the YN2 monolayer is a promising DHM for high-speed spintronic devices and would lead to new opportunities in designing other p-state DHMs.

106 citations

Network Information
Related Topics (5)
Magnetization
107.8K papers, 1.9M citations
90% related
Band gap
86.8K papers, 2.2M citations
87% related
Thin film
275.5K papers, 4.5M citations
87% related
Amorphous solid
117K papers, 2.2M citations
86% related
Quantum dot
76.7K papers, 1.9M citations
86% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20238
202211
202126
202030
201936
201819