Physical Review B

Antiferromagnetic materials could represent the future of spintronic applications thanks to the numerous interesting features they combine: they are robust against perturbation due to magnetic fields, produce no stray fields, display ultrafast dynamics and are capable of generating large magneto-transport effects Intense research efforts over the past decade have been invested in unraveling spin transport properties in antiferromagnetic materials Whether spin transport can be used to drive the antiferromagnetic order and how subsequent variations can be detected are some of the thrilling challenges currently being addressed Antiferromagnetic spintronics started out with studies on spin transfer, and has undergone a definite revival in the last few years with the publication of pioneering articles on the use of spin-orbit interactions in antiferromagnets This paradigm shift offers possibilities for radically new concepts for spin manipulation in electronics Central to these endeavors are the need for predictive models, relevant disruptive materials and new experimental designs This paper reviews the most prominent spintronic effects described based on theoretical and experimental analysis of antiferromagnetic materials It also details some of the remaining bottlenecks and suggests possible avenues for future research

Antiferromagnetic spintronics

Charge separation is crucial for increasing the activity of semiconductor-based photocatalysts, especially in water splitting reactions. Here we show, using monoclinic bismuth vanadate crystal as a model photocatalyst, that efficient charge separation can be achieved on different crystal facets, as evidenced by the reduction reaction with photogenerated electrons and oxidation reaction with photogenerated holes, which take place separately on the {010} and {110} facets under photo-irradiation. Based on this finding, the reduction and oxidation cocatalysts are selectively deposited on the {010} and {110} facets respectively, resulting in much higher activity in both photocatalytic and photoelectrocatalytic water oxidation reactions, compared with the photocatalyst with randomly distributed cocatalysts. These results show that the photogenrated electrons and holes can be separated between the different facets of semiconductor crystals. This finding may be useful in semiconductor physics and chemistry to construct highly efficient solar energy conversion systems.

/pdf/spatial-separation-of-photogenerated-electrons-and-holes-396qh4w4yc.pdf

Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4

Visible-light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross-coupling reactions, α-amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible-light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible-light-absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo- or metal catalysis.

Visible-Light Photocatalysis: Does It Make a Difference in Organic Synthesis?

The manipulation of magnetic properties by an electric field in magnetoelectric multiferroic materials has driven significant research activity, with the goal of realizing their transformative technological potential. Here, we review progress in the fundamental understanding and design of new multiferroic materials, advances in characterization and modelling tools to describe them, and the exploration of devices and applications. Focusing on the translation of the many scientific breakthroughs into technological innovations, we identify the key open questions in the field where targeted research activities could have maximum impact in transitioning scientific discoveries into real applications. Magnetoelectric multiferroics, where magnetic properties are manipulated by electric field and vice versa, could lead to improved electronic devices. Here, advances in materials, characterisation and modelling, and usage in applications are reviewed.

Advances in magnetoelectric multiferroics.

Understanding interfacial phenomena is crucial for precise control in the growth of materials for advanced semiconductor devices. A systematic in situ coverage dependent study is conducted to study the Schottky barrier evolution and chemical reactions at the yttrium/germanium interface. Adatom-induced band bending is present in the early growth stages while metal-induced gap states resulted in strong Fermi level pinning at larger yttrium (Y) thicknesses. Furthermore, significant intermixing occurs at 3 A thickness of Y and saturates at 17 A of Y. The underlying mechanism behind this self-limiting intermixing is well-described by a combination of chemical bond and metal-induced weakening theories. The implications of our findings on device performance are discussed.

Formation of the yttrium/germanium interface: Fermi-level pinning and intermixing at room temperature

Noncollinear Mn3Sn for Antiferromagnetic Spintronics

Antiferromagnetic spintronics is one of the leading candidates for next-generation electronics. Among abundant antiferromagnets, noncollinear antiferromagnets are promising for achieving practical applications due to coexisting ferromagnetic and antiferromagnetic merits. In this perspective, we briefly review the recent progress in the emerging noncollinear antiferromagnetic spintronics from fundamental physics to device applications. Current challenges and future research directions for this field are also discussed.

https://matlab.labapress.com/data/article/export-pdf?id=62dc6fa7e8278b03f88a36e5

Noncollinear Antiferromagnetic Spintronics

The magnetic structure of exchange-coupled antiferromagnetic (AF) layers in epitaxial $\mathrm{L}{\mathrm{a}}_{0.7}\mathrm{S}{\mathrm{r}}_{0.3}\mathrm{Mn}{\mathrm{O}}_{3}$ (LSMO)/$\mathrm{L}{\mathrm{a}}_{0.7}\mathrm{S}{\mathrm{r}}_{0.3}\mathrm{Fe}{\mathrm{O}}_{3}$ (LSFO) superlattices grown on (111)-oriented $\mathrm{SrTi}{\mathrm{O}}_{3}$ substrates was studied using angle-dependent x-ray absorption spectroscopy utilizing linearly polarized x rays. We demonstrate the development of the measurement protocols needed to determine the orientation of the LSFO antiferromagnetic spin axis and how it responds to an applied magnetic field due to exchange interactions with an adjacent ferromagnetic layer. A small energy difference exists between two types of AF order: the majority of the AF moments cant out-of-the-plane of the film along the 110 or 100 directions depending on the LSFO layer thickness. In response to an applied magnetic field, these canted moments are aligned with a single 110 or 100 direction that maintains a nearly perpendicular orientation relative to the LSMO sublayer magnetization. The remaining AF moments lie within the $(111)$ plane and these in-plane moments can be reoriented to an arbitrary in-plane direction to lie parallel to the LSMO sublayer magnetization. These results demonstrate that the magnetic order of AF thin films and heterostructures is far more complex than in bulk LSFO and can be tuned with orientation, thickness, and applied magnetic field.

/pdf/antiferromagnetic-structure-of-exchange-coupled-l-a-0-7-s-r-3gu9p480ms.pdf

Zhiqi Liu

Papers

Formation of the yttrium/germanium interface: Fermi-level pinning and intermixing at room temperature

Noncollinear Mn3Sn for Antiferromagnetic Spintronics

Noncollinear Antiferromagnetic Spintronics

Antiferromagnetic structure of exchange-coupled L a 0.7 S r 0.3 Fe O 3 thin films studied using angle-dependent x-ray absorption spectroscopy

Band gap, band offsets and dielectric constant improvement by addition of yttrium into lanthanum aluminate