Low-Temperature Spin-Canted Magnetism and Bipolaron Freezing Electrical Transition in Potential Electron Field Emitter NdNiO₃

Abstract

The orthorhombic nanostructured NdNiO3 is prepared by the sol–gel auto-combustion method, and its temperature-dependent magnetic and electrical transport properties are studied. The electric field emission with density functional theory and current voltage characteristics are also investigated at room temperature. The low-temperature magnetic measurement (magnetization with field and temperature) shows that NdNiO3 undergoes a magnetic phase transition (T N) near 176 K from paramagnetic to spin-canted antiferromagnetic state. The temperature-dependent magnetic susceptibility (χ) reinforced the signature of magnetic phase transition, and it is fitted by the modified Curie–Weiss law. A metal to insulator (MIT) phase transition (∼178 K) is observed above T N from temperature- and frequency-dependent conductivity measurement. It originates due to higher distortion of NiO6 octahedra and bandwidth constriction of NdNiO3 nanostructured compound. The variation of the frequency exponent (n) with temperature illustrates the continuous-time random walk conduction model with bipolaron condensation near MIT and the non-overlapping small polaron tunneling model above room temperature. The spin-resolved density of states calculation exhibits the room temperature paramagnetic phase and metallic nature and helps us to calculate local work function (Φ) ∼5.44 eV. Low turn-on field at 1 μA/cm2 ∼10.5 V/μm and high field emission current density 203 μA/cm2 at 21 V/μm are observed for layered NdNiO3 with a field enhancement factor (β) ∼1230, which promotes NdNiO3 as an efficient field emitter. The current–voltage characteristics of NdNiO3/p-Si heterostructures are also explored for future technological applications.

Energy Transfer and Self-Trapping Exciton Luminescence in Sb3+-Doped Two-Dimensional Layered Dion–Jacobson Phase Cadmium-Based Perovskites

“…While Δ A decreases with longer wavelengths (Figure S17a,b), the overall trend is in agreement with the false color plots shown in Figure a,b. In the undoped sample, the TA occurs mainly from the phonon-coupled electronic states in the range of 400–605 nm with a biexciton nature (Δ A > 0) as shown in Figure a, while the doped sample has a much wider phonon-coupled electronic state in the range of 400–800 nm with the biexcitonic nature and longer time scale, − as shown in Figure b. This implies that there is a broader electronic energy distribution after Cd–Sb neighboring coupling after Sb doping.…”

Electric-Field Emission Mechanism in Q-Carbon Field Emitters

“…The three-dimensional (3D) electron density distribution of Q-carbon is calculated by maximizing the entropy ( S ) under some constraints and the maximum entropy method (MEM) pattern gives valuable information about the electron richness along the Q-carbon emission surface. The MEM pattern is shown in Figure b, and it is calculated by , S = prefix− ∑ k = 1 N ρ k .25em nobreak0em0.25em⁢ ln ( ρ k τ k ) where ρ normalk = ρ normalk * ∑ k = 1 N ρ normalk * …”

Tubular Diamond as an Efficient Electron Field Emitter

“…Thus, electron emission can occur in different ways such as increasing temperature (thermionic emission), particle irradiation (secondary emission), or lowering the potential barrier by applying an electric field (∝– eEx ). Therefore, the effective potential barrier becomes thinner (triangular), and the effective barrier height is lowered . The effective NEA of diamond occurred due to depletion band bending at the surface where the vacuum level shifted at an energy level below the CB minima and it can be defined as, χ eff = φ BB – χ; where φ BB is the band bending and χ true electron affinity of diamond .…”

“…Therefore, the effective potential barrier becomes thinner (triangular), and the effective barrier height is lowered. 48 The effective NEA of diamond occurred due to depletion band bending at the surface where the vacuum level shifted at an energy level below the CB minima and it can be defined as, χ eff = φ BB − χ; where φ BB is the band bending and χ true electron affinity of diamond. 8 The electron emission starts from the surface through a quantum mechanical tunneling process and the experimental setup for electric field emission is also shown inset of Figure 6a.…”