ABSTRACT
Modulating semiconducting channel potential has been used for electrical switching in transistors without biological plasticity operations that are critical for energy-efficient neuromorphic computing. To achieve efficient data processing, alternative transport mechanisms, such as tunneling and thermionic emission, have been introduced with 2D materials. Here, a polymorphic memtransistor based on atomically thin Mo0.91 W0.09 Te2 is presented, where the lattice and electronic structures of the lateral device channel can be tuned as either metallic (1T') or semiconducting (2H) phases by electrical gating. The structural and electronic phase change of the channel material, optimized in Mo0.91 W0.09 Te2 , is explored using transport and optical measurements at the device scale. Based on the phase transition, the polymorphic memtransistor demonstrates a high on/off ratio (up to 105 ), low subthreshold swing (down to 80 mV dec-1 ), and various memristive behaviors, which are distinguished from traditional phase-change memory, transistors, and passive memristors for diverse neuromorphic and in-memory computing.
ABSTRACT
NiTe2, a type-II Dirac semimetal with a strongly tilted Dirac band, has been explored extensively to understand its intriguing topological properties. Here, using density functional theory calculations, we report that the strength of the spin-orbit coupling (SOC) in NiTe2 can be tuned by Se substitution. This results in negative shifts of the bulk Dirac point (BDP) while preserving the type-II Dirac band. Indeed, combined studies using scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy confirm that the BDP in the NiTe2-xSex alloy moves from +0.1 eV (NiTe2) to -0.3 eV (NiTeSe) depending on the Se concentrations, indicating the effective tunability of type-II Dirac Fermions. Our results demonstrate an approach to tailor the type-II Dirac band in NiTe2 by controlling the SOC strength via chalcogen substitution. This approach can be applicable to different types of topological materials.
ABSTRACT
Polymorphism allows the symmetry of the lattice and spatial charge distributions of atomically thin materials to be designed. While various polymorphs for superconducting, magnetic, and topological states have been extensively studied, polymorphic control is a challenge for robust ferroelectricity in atomically thin geometries. Here, the atomic and electric manipulation of ferroelectric polymorphs in Mo1- x Wx Te2 is reported. Atomic manipulation for polymorphic control via chemical pressure (substituting tungsten for molybdenum atoms) and charge density modulation can realize tunable polar lattice structures and robust ferroelectricity up to T = 400 K with a constant coercive field in an atomically thin material. Owing to the effective inversion symmetry breaking, the ferroelectric switching withstands a charge carrier density of up to 1.1 × 1013 cm-2 , developing an original diagram for ferroelectric switching in atomically thin materials.
ABSTRACT
From Aug-2000 to Aug-2003 at HCM City Blood Transfusion and Hematology hospital, 31 cases of endoscopic splenectomy were studied to evaluate the effect of this surgery to treat chronical immuno-thrombocytopenic purpurea once corticotherapy and immunosupressive therapy failed. Results showed that one year after splenectomy, 64,52 – 76,92%, and 2 years after, 50% of cases had had completely positive response. There was absolute failure in 38,7% of cases within 3 first months, but from the 4th month, there was no relapse case. A half number of patients with failed splenectomy had had quick response to corticotherapy more.The duration of treatment was short, endoscopic splenectomy was safe. There was no death. No case of blood transfusion was needed. There were no complications
