Search

We report on electrical gating of superconducting bilayer NbSe2 using dual-gate field-effect transistors constructed by the van der Waals assembly of mechanically exfoliated NbSe2 and SrTiO3 thin films grown by molecular beam epitaxy. Charge carrier doping, but not a pure electric field, was found to induce changes to the superconducting resistive transition, reaching a 190 mK modulation of the critical temperature and excluding the Rashba effect. The phase space for the superconducting state beyond the Pauli limit under in-plane magnetic fields expands when the critical temperature is enhanced. Quantitative comparison with theory suggests the presence of intervalley scattering, which competes with Ising spin–orbit coupling to set the superconducting-normal phase boundary. The gating method demonstrated here may be applied to study other van der Waals layered superconductors. [ABSTRACT FROM AUTHOR]

Epitaxial near-stoichiometric ferroelectric Pb(Zr0.53Ti0.47)O3 thin films were fabricated on epitaxial metallic LaNiO3 electrodes deposited on (001) SrTiO3 and (001) LaAlO3 single crystal substrates by pulsed laser ablation. The P–E hysteresis loop of PZT in the trilayer of Ag/PZT/LNO/STO was measured using the Sawyer–Tower circuit. The remnant polarization Pr and coercive field Ec at room temperature were 30 μC/cm2 and 69.3 kV/cm (peak-to-peak voltage=30 V, 50 Hz), respectively. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A HfO2-based thin film is a nanoscale ferroelectric material with a high-k dielectric and CMOS compatibility, which make it a promising candidate for high-performance electronics. Here, we demonstrate the synthesis of a ferroelectric Y-doped HfO2 (HYO) thin film by pulsed laser deposition. This HYO thin film is gradient doped by alternately depositing a HfO2 ceramic target and a Y2O3 ceramic target. In the films, the orthorhombic phase, ferroelectric phase, is proved by grazing incidence x-ray diffraction and scanning transmission electron microscopy measurements. Moreover, the HYO thin film embraces outstanding ferroelectric and dielectric properties, its remanent polarization is up to 10.5 μC/cm2, and the dielectric constant is 27. The 180° inversion of the domain can be observed in a piezoelectric power microscopy image, while the phase contrast of the write domain fades with time. Therefore, this work provides a reliable approach to obtain a ferroelectric HYO thin film, which enables great potential in future high-performance nanoelectronics. [ABSTRACT FROM AUTHOR]

B-site Ti-substituted Bi1.5Zn1.0Nb1.5O7 (Bi1.5Zn1.0Nb1.5-xTixO7, x=0, 0.05, and 0.10) thin films have been fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. The x-ray diffraction and scanning electron microscopy measurements show that the films have a single phase and are well crystallized and homogeneous. Dielectric properties are investigated as function of temperature and frequency. It is found that the Ti substitution increases the dielectric constant. At 10 kHz, the room temperature dielectric constant and loss tangent ([variant_greek_epsilon], tan δ) are (163, 0.006), (182, 0.014), (197, 0.010) for the films with x=0, 0.05, and 0.10, respectively. In a wide temperature and frequency range (-100 °C∼50 °C, 1 kHz∼1 MHz), the dielectric constant is almost constant. However, below -100 °C, a dielectric relaxation depending on Ti content is observed. The relationship between structure and property of this thin film system is discussed. [ABSTRACT FROM AUTHOR]