Tuning of the metal-insulator transition in La0.75Sr0.25MnO3∕PrBa2Cu3O7−δ superlattices

Abstract

We have investigated the magnetotransport and magnetic properties of La0.75Sr0.25MnO3∕PrBa2Cu3O7−δ superlattices. Magnetic hysteresis loops show the expected ferromagnetic behavior, although the saturation magnetization is smaller than the expected value based on nominal layer thickness. We find that the electric transport on the superlattices can be qualitatively described using a simple layers-in-parallel model. We also find that the temperature at which the peak of the resistivity curve is located, and in consequence the temperature at which the maximum of the magnetoresistance curve are observed, are a function of layer thickness. The superlattices show an appreciable magnetoresistance for low temperatures, which may be consequence of a spin canted or weak antiferromagnetic manganite phase stabilized at the interfaces.

Enhanced leakage current properties of Ni-doped Ba0.6Sr0.4TiO3 thin films driven by modified band edge state

“…10͒ could induce the low operating voltages of ZnO TFTs. 5,8,9,15 This poor leakage current is closely related to the material properties of room temperature ͑RT͒deposited high-k dielectrics, since the gate dielectrics for transparent TFTs cannot often be annealed at high temperature due to the limited thermal stability of transparent glasses substrates. 7,[11][12][13][14] In addition, the thickness of high-k gate oxides should be over 200 nm when the TFTs are fabricated on rough plastic substrates to avoid the pin hole problems that are detrimental to ZnO-TFT operation.…”

Electrically stable low voltage operating ZnO thin film transistors with low leakage current Ni-doped Ba0.6Sr0.4TiO3 gate insulator

“…Therefore, the use of high-k gate dielectrics with thicknesses over 200 nm is optimal for stable operation of low voltage ZnO-TFTs. While there have been some promising early results for near room temperature grown high-K gate insulators, including barium zirconium titanate (BZT) [8], Bi 1.5 Zn 1.0 Nb 1.5 O 7 (BZN) [2,3,4], Al 2 O 3 [9], HfO 2 [9,10], and TiO 2 [11], they generally suffer from poor leakage current characteristics at voltages above 5 V. The authors recently developed Mn-doped Ba 0.6 Sr 0.4 TiO 3 (BST) thin films deposited at room temperature as a potential candidate for gate insulators [12]. The Mn-doped BST films could provide the required high dielectric constant (∼24) coupled with enhanced leakage current characteristics.…”

“…Transparent ZnO films are used as active channel materials, which exhibit n-type semiconductor characteristics with high optical transmittance in the visible spectrum and a wide band gap of 3.3 eV [1,2]. ZnO thin-film transistors (TFTs) are of particular interest because of their potential to replace hydrogenated amorphous or polycrystalline silicon (a-Si/H or poly-Si) TFTs.…”

Quasi-Random Resistor Network Model for Linear Magnetoresistance of Metal–Semiconductor Composite

“…The two constraint conditions are as follows: (1) The boundary values of µ are the mobility of silver metal µ 1 and semiconductor µ 2 , respectively. (2) The average value of µ is described by the parallel connection model of composite, [17] i.e., μ = f µ 1 + (1 − f )µ 2 . Based on Eqs.…”