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In quantum systems, signatures of multifractality are rare. They have been found only in the multiscaling of eigenfunctions at critical points. Here we demonstrate multifractality in the magnetic field-induced universal conductance fluctuations of the conductance in a quantum condensed matter system, namely, high-mobility single-layer graphene field-effect transistors. This multifractality decreases as the temperature increases or as doping moves the system away from the Dirac point. Our measurements and analysis present evidence for an incipient Anderson-localization near the Dirac point as the most plausible cause for this multifractality. Our experiments suggest that multifractality in the scaling behavior of local eigenfunctions are reflected in macroscopic transport coefficients. We conjecture that an incipient Anderson-localization transition may be the origin of this multifractality. It is possible that multifractality is ubiquitous in transport properties of low-dimensional systems. Indeed, our work suggests that we should look for multifractality in transport in other low-dimensional quantum condensed-matter systems. Multifractality is ubiquitous in classical systems but rare in quantum ones. Here the authors present observations demonstrating that universal conductance fluctuations in high-mobility single-layer graphene field-effect transistors are multifractal and may arise from Anderson-localization.

Sensing of mechanical stimuli forms an important communication pathway between humans/environment and machines. The progress in such sensing technology has possible impacts on the functioning of automated systems, human machine interfacing, health-care monitoring, prosthetics and safety systems. The challenges in this field range from attaining high sensitivity to extreme robustness. In this article, sensing of complex mechanical stimuli with a patch of taped crumpled reduced graphene oxide (rGO) has been reported which can typically be assembled under household conditions. The ability of this sensor to detect a wide variety of pressures and strains in conventional day-to-day applications has been demonstrated. An extremely high gauge factor (similar to 10(3)) at ultralow strains (similar to 10(-4)) with fast response times (

In this paper we present a method for sensing of chemical vapour based on scaling of resistance fluctuation of single layer graphene (SLG) field effect transistors. Increase of variance of resistance fluctuation of device in presence of chemical vapour makes noise a very sensitive tool for detection. Analysis of the effect of presence of chemicals in the ambience of graphene on the 1/f noise spectrum is analyzed. Change in noise presents a method of detection with sensitivity and specificity, with response times much smaller than timescales related to resistance change.

In this letter, we present the results of systematic experimental investigations of the effect of different chemical environments on the low frequency resistance fluctuations of single layer graphene field effect transistors. The shape of the power spectral density of noise was found to be determined by the energetics of the adsorption-desorption of molecules from the graphene surface making it the dominant source of noise in these devices. We also demonstrate a method of quantitatively determining the adsorption energies of chemicals on graphene surface based on noise measurements. We find that the magnitude of noise is extremely sensitive to the nature and amount of the chemical species present. We propose that a chemical sensor based on the measurement of low frequency resistance fluctuations of single layer graphene field effect transistor devices will have extremely high sensitivity, very high specificity, high fidelity, and fast response times. (c) 2015 AIP Publishing LLC.

Detailed experimental and theoretical studies of the temperature dependence of the effect of different scattering mechanisms on electrical transport properties of graphene devices are presented. We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering. On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities. The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms., Comment: Accepted for Publication in Scientific Reports, 2015

One of the most interesting predicted applications of graphene monolayer based devices is as high quality sensors. In this letter we show, through systematic experiments, a chemical vapor sensor based on the measurement of low frequency resistance fluctuations of single layer graphene field-effect-transistor (SLG-FET) devices. The sensor has extremely high sensitivity, very high specificity, high fidelity and fast response times. The performance of the device using this scheme of measurement (which uses resistance fluctuations as the detection parameter) is more than two orders of magnitude better than a detection scheme where changes in the average value of the resistance is monitored. We propose a number-density fluctuation based model to explain the superior characteristics of noise measurement based detection scheme presented in this article.