Heusler 4.0: Tunable Materials

Wollmann, Lukas; Nayak, Ajaya K.; Parkin, Stuart S. P.; Felser, Claudia

doi:10.1146/annurev-matsci-070616-123928

Cited by 168 publications

(104 citation statements)

References 131 publications

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“…To advance in this field, there is a clear need for novel materials, as well as material combinations, which-depending on the application-could provide a large degree of spin polarization, strong anisotropies, low to no magnetization and ensure efficient conversion between spin and charge currents. In this respect, materials which are and will be intensively explored are asymmetrically sandwiched ultrathin ferromagnetic metals [19], Heusler alloys [32], Weyl semimetals [33] and magnetoelectric materials [34] to name just a few. These materials form the heart of novel concepts for antiferromagnetic spintronics (section 12), spin-orbitronics and oxitronics.…”

Section: Denys Makarovmentioning

confidence: 99%

The 2017 Magnetism Roadmap

Sander

Valenzuela

Makarov

et al. 2017

J. Phys. D: Appl. Phys.

326

207

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Building upon the success and relevance of the 2014 Magnetism Roadmap, this 2017 Magnetism Roadmap edition follows a similar general layout, even if its focus is naturally shifted, and a different group of experts and, thus, viewpoints are being collected and presented. More importantly, key developments have changed the research landscape in very relevant ways, so that a novel view onto some of the most crucial developments is warranted, and thus, this 2017 Magnetism Roadmap article is a timely endeavour. The change in landscape is hereby not exclusively scientific, but also reflects the magnetism related industrial application portfolio. Specifically, Hard Disk Drive technology, which still dominates digital storage and will continue to do so for many years, if not decades, has now limited its footprint in the scientific Topical ReviewOriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. and research community, whereas significantly growing interest in magnetism and magnetic materials in relation to energy applications is noticeable, and other technological fields are emerging as well. Also, more and more work is occurring in which complex topologies of magnetically ordered states are being explored, hereby aiming at a technological utilization of the very theoretical concepts that were recognised by the 2016 Nobel Prize in Physics.Given this somewhat shifted scenario, it seemed appropriate to select topics for this Roadmap article that represent the three core pillars of magnetism, namely magnetic materials, magnetic phenomena and associated characterization techniques, as well as applications of magnetism. While many of the contributions in this Roadmap have clearly overlapping relevance in all three fields, their relative focus is mostly associated to one of the three pillars. In this way, the interconnecting roles of having suitable magnetic materials, understanding (and being able to characterize) the underlying physics of their behaviour and utilizing them for applications and devices is well illustrated, thus giving an accurate snapshot of the world of magnetism in 2017.The article consists of 14 sections, each written by an expert in the field and addressing a specific subject on two pages. Evidently, the depth at which each contribution can describe the subject matter is limited and a full review of their statuses, advances, challenges and perspectives cannot be fully accomplished. Also, magnetism, as a vibrant research field, is too diverse, so that a number of areas will not be adequately represented here, leaving space for further Roadmap editions in the future. However, this 2017 Magnetism Roadmap article can provide a frame that will enable the reader to judge where each subject and magnetism research field stands overall today and which directions it might take in the foreseeable future.The first mater...

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Section: Denys Makarovmentioning

confidence: 99%

The 2017 Magnetism Roadmap

Sander

Valenzuela

Makarov

et al. 2017

J. Phys. D: Appl. Phys.

326

207

View full text Add to dashboard Cite

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“…Heusler compounds are known for their multi-functionality and tunability with controllable spin-orbit effects 1,22 therefore, they are ideal materials for spin-orbitronic applications. The fundamental interactions such as SOC and exchange interaction can be microscopically controlled by chemical substitution 22 . For example in Mn x YZ, the 3d transition metal element, Mn, plays a crucial role in exchange interactions and the Y/Z elements are a source of large spin-orbit coupling.…”

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confidence: 99%

Anisotropic topological Hall effect with real and momentum space Berry curvature in the antiskrymion-hosting Heusler compound Mn1.4PtSn

et al. 2019

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The topological Hall effect (THE) is one of the key signatures of topologically non-trivial magnetic spin textures, wherein electrons feel an additional transverse voltage to the applied current. The magnitude of THE is often small compared to the anomalous Hall effect. Here, we find a large THE of 0.9 µΩcm that is of the same order of the anomalous Hall effect in the single crystalline antiskyrmion hosting Heusler compound Mn1.4PtSn, a non-centrosymmetric tetragonal compound. The THE is highly anisotropic and survives in the whole temperature range where the spin structure is noncoplanar (<170 K). The THE is zero above the spin reorientation transition temperature of 170 K, where the magnetization will have a collinear and ferromagnetic alignment. The large value of the THE entails a significant contribution from the momentum space Berry curvature along with real space Berry curvature, which has never been observed earlier.

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“…In fact, there are no adequate theoretical or experimental studies that investigate confinement effects of Heusler compounds to-date from which we could have extracted more accurate information. 30,31 Nevertheless, to obtain a more realistic bandgap behavior with confinement, we estimate the band edges using the approach described in Ref. [23,24].…”

Section: Resultsmentioning

confidence: 99%

Simulation study of ballistic spin-MOSFET devices with ferromagnetic channels based on some Heusler and oxide compounds

Graziosi

Neophytou

2018

Journal of Applied Physics

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Newly emerged materials from the family of Heuslers and complex oxides exhibit finite bandgaps and ferromagnetic behavior with Curie temperatures much higher than even room temperature. In this work, using the semiclassical top-of-the-barrier FET model, we explore the operation of a spin-MOSFET that utilizes such ferromagnetic semiconductors as channel materials, in addition to ferromagnetic source/drain contacts.Such a device could retain the spin polarization of injected electrons in the channel, the loss of which limits the operation of traditional spin transistors with non-ferromagnetic channels. We examine the operation of four material systems that are currently considered some of the most prominent known ferromagnetic semiconductors, three Heusler-type alloys (Mn2CoAl, CrVZrAl, CoVZrAl) and one from the oxide family (NiFe2O4). We describe their bandstructures by using data from DFT calculations. We investigate under which conditions high spin polarization and significant ION/IOFF ratio, two essential requirements for the spin-MOSFET operation, are both achieved. We show that these particular Heusler channels, in their bulk form, do not have adequate bandgap to provide high ION/IOFF ratios, and have small magnetoconductance compared to state-of-the-art devices. However, with confinement into ultra-narrow sizes down to a few nanometers, and by engineering their spin dependent contact resistances, they could prove promising channel materials for the realization of spin-MOSFET transistor devices that offer combined logic and memory functionalities. Although the main compounds of interest in 2 this paper are Mn2CoAl, CrVZrAl, CoVZrAl, and NiFe2O4 alone, we expect that the insight we provide is relevant to other classes of such materials as well.

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Heusler 4.0: Tunable Materials

Cited by 168 publications

References 131 publications

The 2017 Magnetism Roadmap

The 2017 Magnetism Roadmap

Anisotropic topological Hall effect with real and momentum space Berry curvature in the antiskrymion-hosting Heusler compound Mn1.4PtSn

Simulation study of ballistic spin-MOSFET devices with ferromagnetic channels based on some Heusler and oxide compounds

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