Magnetic skyrmions are topologically protected spin textures that are being investigated for their potential use in next generation magnetic storage devices. Here, magnetic skyrmions and other magnetic phases in Fe1−
In bulk chiral crystals, 3D structures of magnetic skyrmions form topologically protected skyrmion strings (SkS) that have shown potential as magnonic nano‐waveguides for information transfer. Although SkS stability is expected to be enhanced in nanostructures of skyrmion‐hosting materials, experimental observation and detection of SkS in nanostructures under an applied in‐plane magnetic field is difficult. Here, temperature‐dependent magnetic field‐driven creation and annihilation of SkS in B20 FeGe nanostructures (nanowires and nanoplates) under in‐plane magnetic field (
- NSF-PAR ID:
- 10452961
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 31
- Issue:
- 13
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract x Cox Ge (x < 0.1) microplates (MPLs) newly synthesized via chemical vapor deposition are studied using both magnetic imaging and transport measurements. Lorentz transmission electron microscopy reveals a stabilized magnetic skyrmion phase near room temperature (≈280 K) and a quenched metastable skyrmion lattice via field cooling. Magnetoresistance (MR) measurements in three different configurations reveal a unique anomalous MR signal at temperatures below 200 K and two distinct field dependent magnetic transitions. The topological Hall effect (THE), known as the electronic signature of magnetic skyrmion phase, is detected for the first time in a Fe1−x Cox Ge nanostructure, with a large and positive peak THE resistivity of ≈32 nΩ cm at 260 K. This large magnitude is attributed to both nanostructuring and decreased carrier concentrations due to Co alloying of the Fe1−x Cox Ge MPL. A consistent magnetic phase diagram summarized from both the magnetic imaging and transport measurements shows that the magnetic skyrmions are stabilized in Fe1−x Cox Ge MPLs compared to bulk materials. This study lays the foundation for future skyrmion‐based nanodevices in information storage technologies. -
Abstract Magnetic skyrmions are topologically nontrivial spin textures with envisioned applications in energy-efficient magnetic information storage. Toggling the presence of magnetic skyrmions via writing/deleting processes is essential for spintronics applications, which usually require the application of a magnetic field, a gate voltage or an electric current. Here we demonstrate the reversible field-free writing/deleting of skyrmions at room temperature, via hydrogen chemisorption/desorption on the surface of Ni and Co films. Supported by Monte-Carlo simulations, the skyrmion creation/annihilation is attributed to the hydrogen-induced magnetic anisotropy change on ferromagnetic surfaces. We also demonstrate the role of hydrogen and oxygen on magnetic anisotropy and skyrmion deletion on other magnetic surfaces. Our results open up new possibilities for designing skyrmionic and magneto-ionic devices.
-
Abstract Room‐temperature magnetic skyrmion materials exhibiting robust topological Hall effect (THE) are crucial for novel nano‐spintronic devices. However, such skyrmion‐hosting materials are rare in nature. In this study, a self‐intercalated transition metal dichalcogenide Cr1+
x Te2with a layered crystal structure that hosts room‐temperature skyrmions and exhibits large THE is reported. By tuning the self‐intercalate concentration, a monotonic control of Curie temperature from 169 to 333 K and a magnetic anisotropy transition from out‐of‐plane to the in‐plane configuration are achieved. Based on the intercalation engineering, room‐temperature skyrmions are successfully created in Cr1.53Te2with a Curie temperature of 295 K and a relatively weak perpendicular magnetic anisotropy. Remarkably, a skyrmion‐induced topological Hall resistivity as large as ≈106 nΩ cm is observed at 290 K. Moreover, a sign reversal of THE is also found at low temperatures, which can be ascribed to other topological spin textures having an opposite topological charge to that of the skyrmions. Therefore, chromium telluride can be a new paradigm of the skyrmion material family with promising prospects for future device applications. -
Abstract The present study investigates the cause of a sharp horizontal (
H ) magnetic depression observed on the dayside during the 2003 Halloween storm, and discusses if the same process could cause the 1,600 nTH depression observed at Colaba during the 1859 Carrington storm. For the HalloweenH depression, it is found that (a) it developed in correlation with southward interplanetary magnetic field (IMF)B Z in the sheath region of a coronal mass ejection; (b) its magnitude decreased significantly with decreasing magnetic latitude; (c) it was highly correlated with westward and eastward sub‐auroral zone magnetic deflections at earlier and later local times, respectively; and (d) the westward auroral electrojet (AEJ) enhanced simultaneously in the entire nightside auroral zone, whereas the enhancement of the dayside eastward AEJ was unclear. These features suggest that the dayside R1‐sense wedge current system, which was driven by dayside magnetic reconnection, was the cause of theH depression, and the associated field‐aligned currents closed primarily with the westward AEJ through the nightside. The ColabaH depression also took place on the dayside and lasted for ∼2 hr. Furthermore, it took place within a few hours after the storm commencement, and the westward AEJ enhanced simultaneously in the dawn sector. These similarities suggest that the dayside wedge current system was also the cause of this historical event. The sharp recovery of the ColabaH depression, which has been a challenge to explain, may be attributed to the decay of this current system due to a northward IMF turning. -
Abstract Organic–inorganic hybrid perovskites (OIHPs) have been explosively investigated mainly due to their potential applications in optoelectronics. Despite the electronic charge transport, phenomena regarding the spin‐polarized electronic transport in OIHPs‐based spintronic devices and the role of ferromagnet/OIHP spinterfaces remain unclear. In this work, the spin injection, accumulation, transport, and detection at room temperature for a vertical perovskite spin valve (PeSV) consisting of Ni/CH3NH3PbI3−
x Clx /Ni is reported. An in‐plane anisotropic magnetoresistance (AMR) and a PeSV related magnetoresistance (MR) show remarkable magnetic switching behaviors due to the formation of Ni/CH3NH3PbI3−x Clx spinterfaces, and the ferromagnetic coupling between two spin quantization axes of the spinterfaces. With assists of capacitance–frequency (C − −f ) measurements under magnetic fields, the spin accumulation that occurs at the Ni/CH3NH3PbI3−x Clx interface can be detected at the spin parallel (↑↑) and antiparallel (↑↓) configurations. Owing to a strong orbital interaction at the Ni/CH3NH3PbI3−x Clx hybrid interface, the spin‐sensitive electron paramagnetic spectroscopy (EPR) reveals significant change of the magnetic moment (µ). It is believed that the solution processed CH3NH3PbI3−x Clx and the formation of the Ni/CH3NH3PbI3−x Clx spinterface may hold an exceptionally important role for future hybrid optospintronic applications.