Transfer Characteristics in Graphene Field-Effect Transistors with Co Contacts

Graphene field-effect transistors with Co contacts as source and drain electrodes show anomalous distorted transfer characteristics. The anomaly appears only in short-channel devices (shorter than approximately 3 micrometers) and originates from a contact-induced effect. Band alteration of a graphene channel by the contacts is discussed as a possible mechanism for the anomalous characteristics observed.Comment: 10 pages, 3 figures, Appl. Phys. Let

Grassmann Manifold Flow

Recently, studies on machine learning have focused on methods that use symmetry implicit in a specific manifold as an inductive bias. In particular, approaches using Grassmann manifolds have been found to exhibit effective performance in fields such as point cloud and image set analysis. However, there is a lack of research on the construction of general learning models to learn distributions on the Grassmann manifold. In this paper, we lay the theoretical foundations for learning distributions on the Grassmann manifold via continuous normalizing flows. Experimental results show that the proposed method can generate high-quality samples by capturing the data structure. Further, the proposed method significantly outperformed state-of-the-art methods in terms of log-likelihood or evidence lower bound. The results obtained are expected to usher in further research in this field of study.Comment: 32 page

Logic Ciucuits Using Solution-processed Single-walled Carbon Nanotue Transistors

This letter reports on the realization of logic circuits employing solution-processed networks of single-walled carbon nanotubes. We constructed basic logic gates (inverter, NAND and NOR) with n- and p-type field-effect transistors fabricated by solution-based chemical doping. Complementary metal-oxide-semiconductor inverters exhibited voltage gains of up to 20, which illustrates the great potential of carbon nanotube networks for printable flexible electronics.Comment: 12 PAGES, 3 FIGURE

Finding the chiral gravitational wave background of an axion-SU(2) inflationary model using CMB observations and laser interferometers

A detection of B-mode polarization of the Cosmic Microwave Background (CMB) anisotropies would confirm the presence of a primordial gravitational wave background (GWB). In the inflation paradigm this would be an unprecedented probe of the energy scale of inflation as it is directly proportional to the power spectrum of the GWB. However, similar tensor perturbations can be produced by the matter fields present during inflation, breaking this simple relationship. It is therefore important to be able to distinguish between different generation mechanisms of the GWB. In this paper, we analyse the detectability of a new axion-SU(2) gauge field model using its chiral, scale-dependent tensor spectrum. We forecast the detectability of the resulting CMB TB and EB cross-correlations by the LiteBIRD satellite, considering the effects of residual foregrounds, gravitational lensing, and for the first time assess the ability of such an experiment to jointly detect primordial TB and EB spectra and self-calibrate its polarimeter. We find that LiteBIRD will be able to detect the chiral signal for $r_*>0.03$ with $r_*$ denoting the tensor-to-scalar ratio at the peak scale, and that the maximum signal-to-noise for $r_*<0.07$ is $\sim 2$. We go on to consider an advanced stage of a LISA-like mission, and find that such experiments would complement CMB observations by providing sensitivity to GWB chirality on scales inaccessible to the CMB. We conclude that in order to use the CMB to distinguish this model from a conventional vacuum fluctuation model two-point statistics provide some power, but to achieve high statistical significance we would require higher order statistics which take advantage of the model's non-Gaussianity. On the other hand, in the case of a spectrum peaked at very small scales, inaccessible to the CMB, a highly significant detection could be made using space-based laser interferometers.Comment: 24 pages, 12 figures, accepted by PhysRev