We present a density functional theory study of 3d transition-metal (TM) atoms (Sc–Zn) adsorbed on a phosphorene sheet. We show that due to the existence of lone pair electrons on P atoms in phosphorene, all the TM atoms, except the closed-shell Zn atom, can bond strongly to the phosphorene with sizable binding energies. Moreover, the TM@phosphorene systems for TM from Sc to Co exhibit interesting magnetic properties, which arise from the exchange splitting of the TM 3d orbitals. We also find that strain is an effective way to control the magnetism of TM@phosphorene systems by tuning the interaction of the TM with phosphorene and, thus, the relative positions of in-gap TM 3d orbitals. In particular, a small biaxial strain could induce a magnetic transition from a low-spin to a high-spin state in phosphorene decorated by Sc, V, or Mn. These results clearly establish the potential for phosphorene utilization in innovative spintronic devices.

A key challenge in manipulating the magnetization in heavy-metal/ferromagnetic bilayers via the spin-orbit torque is to identify materials that exhibit an efficient charge-to-spin current conversion. Ab initio electronic structure calculations reveal that the intrinsic spin Hall conductivity (SHC) for pristine β-W is about sixty percent larger than that of α-W. More importantly, we demonstrate that the SHC of β-W can be enhanced via Ta alloying. This is corroborated by spin Berry curvature calculations of W 1−x Ta x (x ∼ 12.5%) alloys which show a giant enhancement of spin Hall angle of up to ≈ −0.5. The underlying mechanism is the synergistic behavior of the SHC and longitudinal conductivity with Fermi level position. These findings, not only pave the way for enhancing the intrinsic spin Hall effect in β-W, but also provide new guidelines to exploit substitutional alloying to tailor the spin Hall effect in various materials.

it has been demonstrated recently that the residual water would exist ubiquitously within the ionic liquid (IL) when experiments performed in the air. [11][12][13][14] The water molecular would facilitate the electrochemical reaction through electrolysis into H + and O 2ions, which would then be inserted into materials depending on the polarity of the gating bias [11][12][13][14][15][16][17] (as shown in Figure 1a). Clearly, the electrochemical reaction related modulation is a bulk effect, and therefore its associated charge modulation should not be confined by the 2D limit as the conventional ILG, which is about 10 15 cm −2 at the sample surface. [2][3][4][5][6][7][8] Along these studies, the H + (proton) ion, the smallest and lightest ion, emerges as an ideal candidate to incorporate into materials for the manipulation of band filling via charge neutrality induced electron doping with positively charged proton. [13,18] Besides, protonated materials have tremendous application potential in hydrogen storage [18] and fuel cells. [19][20][21][22] So the study of ILG induced protonation is significant for both fundamental physics (realizing electron doping and phase control) and industry application (discovering new protonated functional materials). It is important to note that although the ILG induced protonation Ionic-liquid-gating-(ILG-) induced proton evolution has emerged as a novel strategy to realize electron doping and manipulate the electronic and magnetic ground states in complex oxides. While the study of a wide range of systems (e.g., SrCoO 2.5 , VO 2 , WO 3 , etc.) has demonstrated important opportunities to incorporate protons through ILG, protonation remains a big challenge for many others. Furthermore, the mechanism of proton intercalation from the ionic liquid/solid interface to whole film has not yet been revealed. Here, with a model system of inverse spinel NiCo 2 O 4 , an increase in system temperature during ILG forms a single but effective method to efficiently achieve protonation. Moreover, the ILG induces a novel phase transformation in NiCo 2 O 4 from ferrimagnetic metallic into antiferromagnetic insulating with protonation at elevated temperatures. This study shows that environmental temperature is an efficient tuning knob to manipulate ILG-induced ionic evolution. Electron Doping

Topological semimetals (TSMs) in which conduction and valence bands cross at zero-dimensional (0D) Dirac nodal points (DNPs) or 1D Dirac nodal lines (DNLs), in 3D momentum space, have recently drawn much attention due to their exotic electronic properties. Here we generalize the TSM state further to a higher-dimensional Dirac nodal sphere (DNS) or pseudo DNS (PDNS) state, with the band crossings forming a 2D closed or approximate sphere at the Fermi level. This new TSM state can exhibit unique electronic properties, making DNS/PDNS a new type of fermion beyond DNP/DNL paradigm. In the realistic crystals, we demonstrate two possible types of PDNS states underlied by different crystalline symmetries, which are characterized with a spherical backbone consisting of multiple DNLs and approximate band degeneracy in between the DNLs. We identify all the possible band crossings with pairs of 1D irreducible representations to form the PDNS states in 32 point groups. Importantly, we discover that strained M H3 (M = Y, Ho, Tb, Nd) and Si3N2 are materials candidates to realize these two types of PDNS states, respectively. As a high-symmetryrequired state, the PDNS semimetal can be regarded as the "parent phase" for other topological gapped and gapless states.