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Science and Technology, NO-7491 Trondheim, Norway ‡ These two authors contribute equally to this work Keywords: Magnetic insulator, SOT switching, Dzyaloshinskii-Moriya interaction, Chiral domain wall, Skyrmion. The interfacial Dzyaloshinskii-Moriya interaction (DMI) in multilayers of heavy metal and ferromagnetic metals enables the stabilization of novel chiral spin structures such as skyrmions. Magnetic insulators, on the other hand can exhibit enhanced dynamics and properties such as lower magnetic damping and therefore it is of interest to combine the properties enabled by interfacial DMI with insulating systems. Here, we demonstrate the presence of interfacial DMI in heterostructures that include insulating magnetic layers. We use a bilayer of perpendicularly magnetized insulating thulium iron garnet (TmIG) and the heavy metal platinum, and find a surprisingly strong interfacial DMI that, combined with spin-orbit torque results, in efficient switching. The interfacial origin is confirmed through thickness dependence measurements of the DMI, revealing the characteristic 1/thickness dependence with one order of magnitude longer decay length compared to metallic layers. We combine chiral spin structures and spinorbit torques for efficient switching and identify skyrmions that allow us to establish the GGG/TmIG interface as the origin of the DMI.The Dzyaloshinskii-Moriya interaction (DMI), an asymmetric exchange interaction, has been intensely studied due to the formation of chiral spin textures such as magnetic

Recent studies have shown that material structures, which lack structural inversion symmetry and have high spin-orbit coupling can exhibit chiral magnetic textures and skyrmions which could be a key component for next generation storage devices. The Dzyaloshinskii-Moriya Interaction (DMI) that stabilizes skyrmions is an anti-symmetric exchange interaction favoring non-collinear orientation of neighboring spins. It has been shown that material systems with high DMI can lead to very efficient domain wall and skyrmion motion by spin-orbit torques. To engineer such devices, it is important to quantify the DMI for a given material system. Here we extract the DMI at the Heavy Metal (HM) /Ferromagnet (FM) interface using two complementary measurement schemes namely asymmetric domain wall motion and the magnetic stripe annihilation. By using the two different measurement schemes, we find for W(5 nm)/Co 20 Fe 60 B 20 (0.6 nm)/MgO(2 nm) the DMI to be 0.68 ± 0.05 mJ/m 2 and 0.73 ± 0.5 mJ/m 2 , respectively. Furthermore, we show that this DMI stabilizes skyrmions at room temperature and that there is a strong dependence of the DMI on the relative composition of the CoFeB alloy. Finally we optimize the layers and the interfaces using different growth conditions and demonstrate that a higher deposition rate leads to a more uniform film with reduced pinning and skyrmions that can be manipulated by Spin-Orbit Torques.Recent advances in thin film fabrication processes have led to the accelerated development of magnetic storage devices. This has opened exciting areas of research due to the effects occurring at the interface between a heavy metal (HM) and a ferromagnet (FM). This interface is the building block for next generation memory devices such as the Spin-Orbit Torque (SOT) MRAM 1-4 . There are a number of important phenomena associated with the interface 5 : interfacial contributions to the SOTs 6 , interfacial perpendicular anisotropy 7,8 , and interfacial Dzyaloshinskii-Moriya interaction (DMI) 9-12 . DMI is an anti-symmetric exchange interaction which favours non-collinear alignment of neighbouring spins S 1

In general, ilmenite FeTiO 3 is synthesized by solid-state reaction at very high pressure and high temperature. Synthesis of FeTiO 3 is not an easy task as the Fe 2 þ ions are not stable. Therefore, it is really challenging to prepare this material. In this work nano-ilmenite FeTiO 3 was synthesized by the sol-gel method. Structural, optical and magnetic characterizations were performed. The bandgap of FeTiO 3 was determined to be 2.8 eV showing FeTiO 3 as suitable wide bandgap material for technological applications. The FeTiO 3 nanoparticles exhibit weak ferromagnetic properties at and below room temperature. The Né el temperature was observed to be around 52 K.

The in-and out-of-plane lower critical fields and magnetic penetration depths of LiFeAs were examined. The anisotropy ratio ΓH c1 (0) was smaller than the expected theoretical value, and increased slightly with increasing temperature from 0.6Tc to Tc. The small degree of anisotropy was numerically confirmed by considering the electron correlation effect. The temperature dependence of the penetration depths followed a power law (∼ T n ) below 0.3Tc, with n > 3.5 for both λ ab and λc. Based on theoretical studies of iron-based superconductors, these results suggest that the superconductivity of LiFeAs can be represented by an extended s±-wave due to the weak impurity scattering effect. And the magnitudes of the two gaps were also evaluated by fitting the superfluid density for both the in-and out-of-plane directions to the two-gap model. The estimated values for the two gaps are consistent with the results from angle-resolved photoemission spectroscopy and specific-heat experiments.

There are many interests to achieve long-range magnetic order in topological insulators of Bi2Se3 or Bi2Te3 by doping magnetic transition metals such as Fe and Mn. The transition metals act as not only magnetic dopants but also electric dopants because they are usually divalent. However, if the doping elements are rare-earth metals such as Gd, which are trivalent, only magnetic moments can be introduced. We fabricated single crystals of Bi2-xGdxTe3 (0 ≤ × ≤ 0.2), in which we observed magnetic phase change from paramagnetic (PM) to antiferromagnetic (AFM) phase by increasing x. This PM-to-AFM phase transition agrees with the density functional theory calculations showing a weak and short-ranged Gd-Gd AFM coupling via the intervening Te ions. The critical point corresponding to the magnetic phase transition is x = 0.09, where large linear magnetoresistance and highly anisotropic Shubnikov-de Haas oscillations are observed. These results are discussed with two-dimensional properties of topological surface state electrons.

To obtain high catalytic properties, finely modulating the electronic structure and active sites of catalysts is important. Herein, we report the design and economical synthesis of Pd@Pt core–shell nanoparticles for high productivity in the direct synthesis of hydrogen peroxide. Pd@Pt core–shell nanoparticles with a partially covered Pt shell on a Pd cube were synthesized using a simple direct seed-mediated growth method. The synthesized Pd@Pt core–shell nanoparticles were composed of high index faceted Pt on the corners and edges, while the Pd–Pt alloy was located on the terrace area of the Pd cubes. Because of the high-indexed Pt and Pd–Pt alloy sites, the synthesized concave Pd@Pt7 nanoparticles exhibited both high H2 conversion and H2O2 selectivity compared with Pd cubes.