1,721,051 research outputs found
Tailoring phases on the device
No full textA phase engineering strategy, using a device configuration consisting of 2D channel materials and patterned electrodes, has been demonstrated. It achieves various phase configurations of 2D materials and versatile functions that can be tailored in situ.
Topological magnon-polarons in honeycomb antiferromagnets with spin-flop transition
Full text linkWe theoretically investigate the thermal Hall transport of magnon-polarons in
a two-dimensional honeycomb antiferromagnetic insulator under the influence of
a perpendicular magnetic field, varying in strength. The application of a
perpendicular magnetic field induces a magnetic phase transition from the
collinear antiferromagnetic phase to the spin-flop phase, leading to a
significant alteration in Hall transport across the transition point. In this
paper, our focus is on the intrinsic contribution to thermal Hall transport
arising from the magnetoelastic interaction. To facilitate experimental
verification of our theoretical results, we present the dependence of thermal
Hall conductivity on magnetic field strength and temperature.Comment: 10 pages, 6 figure
Modified gap states in Fe/MgO/SrTiO3 interfaces studied with scanning tunneling microscopy
No full textThe geometric and electronic structures of Fe islands on MgO film layers were studied with scanning tunneling microscopy and spectroscopy. The MgO layers were grown on a Nb-doped single crystal SrTiO3 (100) surface. Deposited Fe atoms aggregate into islands, the height and diameter of which are about 2.5 and 9.4 nm respectively. Fe islands modify the electronic structure of MgO surface; a ring type depression in the scanning tunneling microscope topography appears by lowered local electron density of states around Fe islands. We find that adsorbed Fe atoms reduce the gap states of MgO layers around Fe islands, which is attributed to the reason for the depletion of the electronic density of states.close1
Memory and Synaptic Devices Based on Emerging 2D Ferroelectricity
No full textMemory devices are an essential part of modern electronics. Efforts to move beyond the traditional "read" and "write" of digital information in volatile and non-volatile memory devices are leading to the rapid growth of neuromorphic technology. There is a growing demand for memory devices with continuous memory states with various retention times and greater integration density with more energy-efficient mechanisms. Two types of memory devices (i.e., non-volatile digital memory and neuro-synaptic devices) have been extensively investigated with emerging materials. Among numerous materials for such memory devices, in this review, the authors focus on 2D ferroelectric materials for promising memory and synaptic devices. Three types of memory devices based on 2D ferroelectric materials are classified and discussed here: 1) ferroelectric gating of semiconducting channels, 2) active ferroelectric channels, and 3) ferroelectric tunnel junction devices. It is known that atomically thin geometry competes with ferroelectricity, which can degrade the quality of the devices based on atomically thin ferroelectric materials. Various efforts to resolve the fundamental issue with emerging 2D ferroelectric materials and how they can be used as a critical element for memory and synaptic devices are surveyed.
Structural and quantum-state phase transitions in van der Waals layered materials
No full textVan der Waals layered transition metal dichalcogenides can exist in many different atomic and electronic phases. Such diverse polymorphisms not only provide a route for investigating novel topological states, such as quantum spin Hall insulators, superconductors and Weyl semimetals, but may also have applications in fields ranging from electronic and optical/ quantum devices to electrochemical catalysis. And the methods for triggering robust phase transitions between polymorphs are evolving and diversifying-several growth processes, high-pressure/strain methods, and optical, electronic and chemical treatments have been developed. Here, we discuss recent progress on phase transitions and the related physics in layered materials, and demonstrate unique features compared with conventional solid-state materials.
Coherent Thermoelectric Power from Graphene Quantum Dots
No full textThe quantum confinement of charge carriers has been a promising approach to enhance the efficiency of thermoelectric devices, by lowering the dimension of materials and raising the boundary phonon scattering rate. The role of quantum confinement in thermoelectric efficiency has been investigated by using macroscopic device-scale measurements based on diffusive electron transport with the thermal de Broglie wavelength of the electrons. Here, we report a new class of thermoelectric operation originating from quasibound state electrons in low-dimensional materials. Coherent thermoelectric power from confined charges was observed at room temperature in graphene quantum dots with diameters of several nanometers. The graphene quantum dots, electrostatically defined as circular n-p-n junctions to isolate charges in the p-type graphene quantum dots, enabled thermoelectric microscopy at the atomic scale, revealing weakly localized and coherent thermoelectric power generation. The conceptual thermoelectric operation provides new insights, selectively enhancing coherent thermoelectric power via resonant states of charge carriers in low-dimensional materials.
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