Shivaji University

About: Shivaji University is a education organization based out in Kolhāpur, Maharashtra, India. It is known for research contribution in the topics: Thin film & Scanning electron microscope. The organization has 3078 authors who have published 5295 publications receiving 115397 citations.

Transient chaos in fractional Bloch equations

Abstract: The Bloch equation provides the fundamental description of nuclear magnetic resonance (NMR) and relaxation (T"1 and T"2). This equation is the basis for both NMR spectroscopy and magnetic resonance imaging (MRI). The fractional-order Bloch equation is a generalization of the integer-order equation that interrelates the precession of the x, y and z components of magnetization with time- and space-dependent relaxation. In this paper we examine transient chaos in a non-linear version of the Bloch equation that includes both fractional derivatives and a model of radiation damping. Recent studies of spin turbulence in the integer-order Bloch equation suggest that perturbations of the magnetization may involve a fading power law form of system memory, which is concisely embedded in the order of the fractional derivative. Numerical analysis of this system shows different patterns in the stability behavior for @a near 1.00. In general, when @a is near 1.00, the system is chaotic, while for 0.98 >=@a>= 0.94, the system shows transient chaos. As the value of @a decreases further, the duration of the transient chaos diminishes and periodic sinusoidal oscillations emerge. These results are consistent with studies of the stability of both the integer and the fractional-order Bloch equation. They provide a more complete model of the dynamic behavior of the NMR system when non-linear feedback of magnetization via radiation damping is present.

Ti3C2-Based MXene Oxide Nanosheets for Resistive Memory and Synaptic Learning Applications.

Abstract: MXene, a new state-of-the-art two-dimensional (2D) nanomaterial, has attracted considerable interest from both industry and academia because of its excellent electrical, mechanical, and chemical properties. However, MXene-based device engineering has rarely been reported. In this study, we explored Ti3C2 MXene for digital and analog computing applications by engineering the top electrode. For this purpose, Ti3C2 MXene was synthesized by a simple chemical process, and its structural, compositional, and morphological properties were studied using various analytical tools. Finally, we explored its potential application in bipolar resistive switching (RS) and synaptic learning devices. In particular, the effect of the top electrode (Ag, Pt, and Al) on the RS properties of the Ti3C2 MXene-based memory devices was thoroughly investigated. Compared with the Ag and Pt top electrode-based devices, the Al/Ti3C2/Pt device exhibited better RS and operated more reliably, as determined by the evaluation of the charge-magnetic property and memory endurance and retention. Thus, we selected the Al/Ti3C2/Pt memristive device to mimic the potentiation and depression synaptic properties and spike-timing-dependent plasticity-based Hebbian learning rules. Furthermore, the electron transport in this device was found to occur by a filamentary RS mechanism (based on oxidized Ti3C2 MXene), as determined by analyzing the electrical fitting curves. The results suggest that the 2D Ti3C2 MXene is an excellent nanomaterial for non-volatile memory and synaptic learning applications.

Electrical Conduction and Magnetoelectric Effect in CuFe1.8Cr0.2O4–Ba0.8Pb0.2TiO3 Composites

Abstract: Magnetoelectric composites of CuFe1.8Cr0.2O4– Ba0.8Pb0.2TiO3 were prepared using high temperature solid-state reaction technique. X-ray structural analysis of these composites confirms the presence of both the phases in the composite. Detailed studies of dielectric properties (e′, tan δ and σac) as a function of frequency (100 Hz to 1 MHz) and temperature (30°C to 250°C) show that these compounds exhibit diffuse ferroelectric phase transitions. Results of ac conductivity, dc resistivity and thermoelectric power measurements show that conduction occurs by hopping of charge carriers. The magnetoelectric effect has been studied as a function of intensity of magnetic field. The electrical polarisation was induced in piezoelectric (Ba0.8Pb0.2TiO3) phase as result of strain induced in the ferrite (CuFe1.8Cr0.2O4) phase by the applied magnetic field. The Jahn-Teller distortion caused in the ferrite lattice by Jahn-Teller ions like Cu2+ and Cr3+ is also responsible for the elastic coupling of strain to the Ba0.8Pb0.2TiO3 phase.