Topological insulating graphene is created using decoration of an extremely small quantity of heavy nanoparticles.

No abstract

We have investigated the electric-field effect on the orbital-ordered state of eg electrons for layered manganites Nd1−xSr1+xMnO4 near the phase boundary between antiferro d3x2−r2/d3y2−r2 and ferro d3x2−r2 orbital-ordered phases. By means of a polarization microscope in crossed-Nicol configuration, we can distinguish these two orbital-ordered phases, and observed the electric-field switching between the two phases. This indicates that the electric-field can affect the directional order of orbital, and the system with the two competitive orbital-ordered states bears the orbital analog of the liquid-crystal functionality.

The introduction of spin-orbit interactions (SOIs) and the subsequent appearance of a twodimensional (2D) topological phase are crucial for voltage-controlled and zero-emission energy spintronic devices. In contrast, graphene basically lacks SOIs due to the small mass of the carbon atom, and appropriate experimental reports for SOIs are rare. Here, we control small-amount (cover ratios < 8%) random decoration of heavy nanoparticles [platinum (Pt) or bismuth telluride (Bi2Te3)] onto mono-layer graphene by developing an original nanoneedle method. Xray photoelectron spectra support low-damage and low-contamination decoration of the nanoparticles, suggesting the presence of Bi-C and Te-C coupling orbitals. In the samples, we find particle-density-dependent non-local resistance (RNL) peaks, which are attributed to the (inverse) spin Hall effect (SHE) arising from SOI with energies as large as 30 meV. This is a larger value than in previous reports and supported by scanning tunneling spectroscopy. The present observation should lead to topological phases of graphene, which can be introduced by random decoration with controlled small amounts of heavy nanoparticles, and their applications.