A strong nonlinear optical response of 2D MoSe2 nanoflakes (NFs) through spatial self‐phase modulation (SSPM) and cross‐phase modulation (XPM) induced by nonlocal coherent light–matter interactions is reported. The coherent interaction of light and MoSe2 NFs creates the SSPM of laser beams, forming concentric diffraction rings. The nonlinear refractive index (n2) and third‐order broadband nonlinear optical susceptibility (χ(3)) of MoSe2 NFs are determined from the self‐diffraction pattern at different exciting wavelengths of 405, 532, and 671 nm with varying laser intensity. The evolution and deformation of diffraction ring patterns are observed and analyzed by the “wind‐chime” model and thermal effect. By taking advantage of the reverse saturated absorption of 2D SnS2 NFs compared to MoSe2, an all‐optical diode has been designed with MoSe2/SnS2 hybrid structure to demonstrate the nonreciprocal light propagation. Few other optical devices based on MoSe2 and semiconducting materials such as Bi2Se3, CuPc, and graphene have been investigated. The all‐optical logic gates and all‐optical information conversion have been demonstrated through the XPM technique using two laser beams. The proposed optical scheme based on MoSe2 NFs has been demonstrated as a potential candidate for all‐optical nonlinear photonic devices such as all‐optical diodes and all‐optical switches.

Colossal electroresistance (CER) in manganites, i.e., a large change in electrical resistance under the influence of either an applied electric field or an applied electric current, has often been described as complimentary to the colossal magnetoresistance (CMR) effect. Mixed valent vanadates with active t 2g and empty e g orbitals, unlike manganites, have not naturally been discussed in this context, as double exchange based CMR is not realizable in them. However, presence of coupled spin and orbital degrees of freedom, metal-insulator transition (MIT) accompanied by orbital order-disorder transition, etc., anyway make the vanadates an exciting group of materials. Here we probe a Fe-doped hollandite lead vanadate PbFe 1.75 V 4.25 O 11 (PFVO), which exhibits a clear MIT as a function of temperature. Most importantly, a giant fall in the resistivity, indicative of a CER, as well as a systematic shift in the MIT towards higher temperature are observed as a function of applied electric current. Detailed structural, magnetic, thermodynamic and transport studies point towards a complex interplay between orbital order/disorder effect, MIT and double exchange in this system.

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Resistive random access memory (RRAM) devices are widely considered promising candidates for future memory and logic applications. Though their excellent performances have been reported over the years, resistive switching due to various charge conduction mechanisms is still being debated. Here, we report systematic investigations on resistive switching in a MoSe2-based nonvolatile bipolar memory device by measuring current–voltage characteristics and using low-frequency conductance noise spectroscopy in both low and high resistive states. The memory device was fabricated in a metal–insulator–metal configuration by mixing MoSe2 nanoflakes in a poly­(methyl methacrylate) (PMMA) matrix sandwiched between the top and bottom electrodes. The device shows an appreciable retention capacity and long cycle endurances in the low resistive state (LRS)/high resistive state (HRS) in repeated measurement cycles. The low-frequency conductance fluctuation power spectra show 1/f noise characteristics in the low resistive state and 1/f 2 behavior in the high resistive state. The 1/f 2 characteristics of the noise power spectra indicate the presence of random telegraphic noise. The stochastic analysis of the current fluctuation in the high resistive state further confirms that the enhanced random telegraphic noise originates from the transport of charge carriers by trap-assisted tunneling in the MoSe2@PMMA matrix.