Zn potential, high Zn abundancy, and ease of material handling. In particular, the recent demonstrations of a reversible charging/discharging process with the use of neutral electrolyte have further rekindled strong research interest in ZIB as potential secondary battery. [5][6][7] However, one key challenge in ZIB research is the highly selective cathode material. To date, only a handful of materials such as manganese-based oxides, [8][9][10] vanadium-based oxides, [11][12][13] Prussian blue analogs, [14,15] polyanion compounds, [16] and quinone analogs [17] have been reported as viable ZIB cathode. Out of these materials, MnO 2 is highly favored as ZIB cathode due to its environmental benignity, low cost, and ease of fabrication. As a result, numerous Zn/MnO 2 battery systems have been reported with satisfactory electrochemical performances over the recent years. [18][19][20][21][22] However, such progress has gradually decelerated due to the increasing challenge in enhancing the intrinsic MnO 2 capacity through modifying with different MnO 2 polymorphs, [23,24] or widening the interlayer spacing. [25] This decelerated trend suggests that structural enhancements have eventually reached a bottleneck, and an alternative strategy such as modifying the material surface chemistry should be considered as the next stage in Zn/MnO 2 battery electrochemical performance enhancements.Defect engineering is a powerful technique that can imbue a material with new functionalities such as electronic, magnetic, and optical properties. [26][27][28] Among the different types of defects, oxygen vacancy (V O ) is a particularly important one in modifying the surface chemistry and geometrical configuration of oxides. [29][30][31] Oxygen vacancy can influence the Zn 2+ adsorption on the material surface, whereby the calculated Gibbs free energy of Zn 2+ adsorption provides an estimation gauging the ease of Zn 2+ adsorption/desorption, i.e., reversibility. Our simulation results show that Gibbs free energy of Zn 2+ adsorption on MnO 2 surface is significantly altered when oxygen vacancies are generated into the MnO 2 lattice. Pristine MnO 2 demonstrates a thermodynamically more favorable Zn 2+ adsorption due to its lower Gibbs free energy of Zn 2+ adsorption. However, this phenomenon concurrently hints that the subsequent desorption process would be thermodynamically more unfavorable. This means that, for pristine MnO 2 , once Zn 2+ is adsorbed onto the MnO 2 surface, the strong chemical bonds between Zn and O would hinder the subsequent Zn 2+ desorption process and these undesorbed Zn 2+ A major limitation of MnO 2 in aqueous Zn/MnO 2 ion battery applications is the poor utilization of its electrochemical active surface area. Herein, it is shown that by generating oxygen vacancies (V O ) in the MnO 2 lattice, Gibbs free energy of Zn 2+ adsorption in the vicinity of V O can be reduced to thermoneutral value (≈0.05 eV). This suggests that Zn 2+ adsorption/desorption process on oxygen-deficient MnO 2 is more reversible as compared to pr...

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Topological Hall effect (THE), appearing as bumps and/or dips in the Hall resistance curves, is considered as a hallmark of the skyrmion spin texture originated from the inversion symmetry breaking and spin–orbit interaction. Recently, Néel‐type skyrmion is proposed based on the observed THE in 5d transition metal oxides heterostructures such as SrRuO3/SrIrO3 bilayers, where the interfacial Dzyaloshinskii–Moriya interaction (DMI), due to the strong spin–orbit coupling (SOC) in SrIrO3 and the broken inversion symmetry at the interface, is believed to play a significant role. Here the emergence of THE in SrRuO3 single layers with thickness ranging from 3 to 6 nm is experimentally demonstrated. It is found that the oxygen octahedron rotation in SrRuO3 also has a significant effect on the observed THE. Furthermore, the THE may be continuously tuned by an applied electrical field. It is proposed that the large SOC of Ru ions together with the broken inversion symmetry, mainly from the interface, produce the DMI that is responsible for the observed THE. The emergence of the gate‐tunable DMI in SrRuO3 single layer may stimulate further investigations of new spin–orbit physics in strong SOC oxides.

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Abstract2D transition metal dichalcogenides have attracted much attention in the field of spintronics due to their rich spin‐dependent properties. The promise of highly compact and low‐energy‐consumption spin‐orbit torque (SOT) devices motivates the search for structures and materials that can satisfy the requirements of giant perpendicular magnetic anisotropy (PMA) and large SOT simultaneously in SOT‐based magnetic memory. Here, it is demonstrated that PMA and SOT in a heavy metal/transition metal ferromagnet structure, Pt/[Co/Ni]2, can be greatly enhanced by introducing a molybdenum disulfide (MoS2) underlayer. According to first‐principles calculation and X‐ray absorption spectroscopy (XAS), the enhancement of the PMA is ascribed to the modification of the orbital hybridization at the interface of Pt/Co due to MoS2. The enhancement of SOT by the role played by MoS2 is explained, which is strongly supported by the identical behavior of SOT and PMA as a function of Pt thickness. This work provides new possibilities to integrate 2D materials into promising spintronics devices.