Ag-capped Au nanopillar arrays on a resin supporter (see left upper figure), with a typical adjacent pillar tip gap of 10 nm, show obviously higher surface-enhanced Raman scattering (SERS) sensitivity (right column in red) than that of the bare Au nanopillar array while using 10 nM R6G as probe molecules. The large-area Ag-capped Au nanopillar array has potential in trace detection of special chemicals.

the third method, that is, the introduction of magnetism in graphene with the proximity effect in the interface of magnetic insulators and graphene. Pioneer works have been demonstrated with 3D bulk magnetic insulators like yttrium iron garnet, europium (II) sulfide, and bismuth ferrite. [7][8][9][10][11][12][13][14][15] Due to the short-range nature of the magnetic exchange coupling, a fully 2D van der Waals heterostructures is desired for downsizing the device and introducing magnetic proximity effect (MPE) at the same time. The recent profound discoveries of 2D ferromagnets [16][17][18][19][20][21][22][23][24][25][26][27][28][29] bring the possibility of 2D ferromagnetic van der Waals heterostructures, [30][31][32][33][34][35][36] it is urgent and essential to comprehensively investigate the magnetic coupling between graphene and 2D ferromagnetic materials for developing 2D spintronic devices. Not just the evidence of the existence of MPE in 2D ferromagnetic van der Waals heterostructures, [37,38] here, we report the direct observation of MPE in graphene/CrBr 3 van der Waals heterostructures by probing Zeeman spin Hall effect (ZSHE) through non-local transport measurements. A further quantitative estimation of Zeeman splitting field demonstrates a significant magnetic proximity exchange field even in a low magnetic field. Furthermore, we observe anomalous longitudinal resistance changes at the Dirac point R XX,D with increasing external magnetic field near ν = 0. This may attribute to the MPE induced ground state phases transformation of graphene from the ferromagnetic state at the lower magnetic field and a canted antiferromagnetic state at a higher field in quantum Hall regime.A typical graphene/CrBr 3 van der Waals heterostructure with Hall bar structure for electrical transport measurement is fabricated as shown in Figure 1a. In order to reach the best performance and a substantial MPE in graphene/CrBr 3 heterostructures, we optimize the fabrication process and conditions to achieve the desired heterostructures (see Experimental Section for details). The sample in the final stage is encapsulated and protected by poly(methyl methacrylate) (PMMA), which keeps the device surface away from the moisture and air for cryotemperature tests. The atomic structure of layered CrBr 3 is shown in Figure 1b. The Cr 3+ ions are configured in a honeycomb network, and the green arrows represent the spin direction of Cr atoms, which are found to exhibit a strong ferromagnetic coupling. [39][40][41][42][43][44] The Raman spectra of Figure 1c indicates that the monolayer graphene still preserves a high crystal quality when heterostructured with CrBr 3 layer. The optical image in 2D van der Waals heterostructures serve as a promising platform to exploit various physical phenomena in a diverse range of novel spintronic device applications. Efficient spin injection is the prerequisite for these devices. The recent discovery of magnetic 2D materials leads to the possibility of fully 2D van der Waals spintronics devices by implemen...

Measurement of nonlinear response offers powerful probes of material propertiesnot accessible at linear order, as they follow distinct symmetry requirements 1,2,3,4,5,6 . For instance, unlike the linear Hall effect, the second-order nonlinear Hall effect typically requires the breaking of inversion symmetry rather than time reversal symmetry 1 , and its successful detection in recent experiments on ultrathin WTe2 has attracted significant attention 7,8 . This second-order nonlinear Hall effect could be used to probe the Berry curvature, a band geometric property, in non-magnetic materials, just like the anomalous Hall effect being used to probe the Berry curvature in magnetic materials 9,10 . As another intrinsic band geometric property, the Berry-connection polarizability tensor was theoretically predicted to play a crucial role in high-order responses 11 but not yet experimentally demonstrated. Here, we report for the first time a high-order nonlinear Hall effect in multi-layer 𝑻 𝒅 -MoTe2 samples. Unprecedently, the third-order Hall

A sensitive and selective fluorescent membrane for rapid detection of trace 2,2',4,5,5'-pentachlorinated biphenyl (PCB101) has been achieved by immobilizing the fluorophore phenyl isothiocyanate (PITC) onto porous anodic aluminium oxide (AAO) membrane (denoted as PITC@AAO). The fluorescence of the PITC@AAO membrane is obviously enhanced after titrating the analyte PCB101 into the membrane, being ascribed to the halogen-bonding interaction between the fluorophore PITC and the analyte PCB101. The fluorescence intensity increases with the PCB101 concentration in the low range below 1 ppm, and there exists an approximate linear relationship between the relative fluorescence intensity and the PCB101 concentration in the low range of 1-6 ppb. Moreover, the PITC@AAO membrane shows good selectivity; for example, it is insensitive to common structural analogs (polychlorinated aromatics). The mechanisms of the fluorescence enhancement and the better sensitivity and selectivity of the PITC@AAO membrane to PCB101 than that of PITC/n-hexane solution are also discussed. This work demonstrates that trace (in ppb range) PCBs can be detected by simple fluorescence measurement.