Charge transport in polyaniline heavily doped with p-toluenesulfonic acid

First results of a 3-cm (9.7 GHz) and 2-mm (140 GHz) waveband EPR study of the magnetic and electron-transport properties over a wide temperature range are reported for the crystalline phase of polyaniline highly doped with p-toluenesulfonic acid. The nature of charge carriers was analyzed and the mechanism of charge transport was established. The spin-lattice and spin-spin relaxation times were measured using the continuous saturation technique. Quasi-three-dimensional (Q3D) domains with a high conductivity are formed in polyaniline by doping. The effective electric conductivity of the polymer is determined by Mott Q3D hopping in domains of this type and Q1D variable-range hopping between these domains. There is no correlation between charge transport and spin relaxation processes. Copyright © 2005 by Pleiades Publishing, Inc

Charge transport in polyaniline heavily doped with p-toluenesulfonic acid

First results of a 3-cm (9.7 GHz) and 2-mm (140 GHz) waveband EPR study on the magnetic and electron-transport properties over a wide temperature range are reported for the crystalline phase of polyaniline highly doped with p-toluenesulfonic acid. The nature of charge carriers was analyzed and the mechanism of charge transport was established. The spin-lattice and spin-spin relaxation times were measured using the continuous saturation technique. Quasi-three-dimensional (Q3D) domains with a high conductivity are formed in polyaniline by doping. The effective electric conductivity of the polymer is determined by Mott Q3D hopping in domains of this type and Q1D variable-range hopping between these domains. There is no correlation between charge transport and spin relaxation processes

Multifrequency EPR study of charge transport in doped polyaniline

Polyaniline highly doped with acrylamido-2-methyl-1-propanesulphonic (PANI-AMPSA) and camphorsulfonic (PANI-CSA) acids have been studied at X- (9.50 GHz) and K- (37.5 GHz) bands EPR. Localized Curie-like and mobile Pauli-like spin charge carriers are stabilized in amorphous and crystalline regions of the samples. AC conductivity contributed from these paramagnetic centers was determined. It was shown that, in contrast with PANI-AMPSA, PANI-CSA with higher both d.c. and a.c. conductivity is a more ordered metal with more rigid and planar polymer chains

EPR, charge transport, and spin dynamics in doped polyanilines

Charge transport and magnetic properties of films of polyaniline (PAN) doped with 10-camphorsulfonic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) have been studied by conductivity, magnetic-susceptibility superconducting quantum interference device measurements, and 3-cm and 8-mm electron paramagnetic resonance (EPR) spectroscopy at doping levels (x) from 0.3 to 0.9 over a temperature range from 15 to 300 K. The temperature dependences of conductivities were explained in terms of the advanced multiphase heterogeneous granular metallic (HGM) model with percolation including disordered metallic (DM) and non-metallic (NM) phases. The anomalous conductivity change in the PAN-AMPSAx system at T>240 K was accounted quantitatively for a solid-phase equilibrium with the occurrence of the disordered anion phase from the metallic islands. A means for analysis of the EPR line shape in conducting media has been developed and, with this, conductivity and microwave dielectric constants were estimated and two EPR signals, R1 and R2, were detected in both systems. It was shown that R1 signal belongs to pinned radicals of isolated polymer chains, whereas R2 is the weight-averaged signal, resulting from three types of paramagnetic centers, localized and mobile spins in the NM and DM phases, which interact via exchange. From the temperature and frequency dependences of the R2 linewidth the spin-diffusion parameters for the NM phase in both systems were determined. It was found that the HGM model allows good explanation of both charge transport and spin diffusion in the doped polyaniline films

Multifrequency X,W-band ESR study on photo-induced ion radical formation in solid films of mono- and di-fullerenes embedded in conjugated polymers

Anion-cation radical formation in solid films of M3EH-PPV blended with C60-PCBM, C120-O-PCBM and C60-MDHE, C 120-O-MDHE under diode laser (532 nm) and Xe-lamp light excitation studied by means of X,W-band at temperatures 30-80 K is reported. Subsequent high frequency W-band ESR data demonstrate the reproducible, but variable effect of appreciable dispersion (D) contribution in the ESR spectral line for the di-fullerene anion radicals. It is suggested that the increase of the D part relative to the absorption (A) in the summarized ESR absorption line in blends with difullerenes is caused by the higher value of difullerene medium conductivity. The obtained data are quantitatively discussed by the D/A ∼ F(d/δ) functional dependence in approach of plane film geometry, where d is the film thickness and δ is the skin-depth. The influence of ν-dependent δ at D/A value has been checked using X-band LESR. © 2014 Elsevier Ltd. All rights reserved

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Charge transport in polyaniline heavily doped with p-toluenesulfonic acid

First results of a 3-cm (9.7 GHz) and 2-mm (140 GHz) waveband EPR study of the magnetic and electron-transport properties over a wide temperature range are reported for the crystalline phase of polyaniline highly doped with p-toluenesulfonic acid. The nature of charge carriers was analyzed and the mechanism of charge transport was established. The spin-lattice and spin-spin relaxation times were measured using the continuous saturation technique. Quasi-three-dimensional (Q3D) domains with a high conductivity are formed in polyaniline by doping. The effective electric conductivity of the polymer is determined by Mott Q3D hopping in domains of this type and Q1D variable-range hopping between these domains. There is no correlation between charge transport and spin relaxation processes. Copyright © 2005 by Pleiades Publishing, Inc

Charge transport in polyaniline heavily doped with p-toluenesulfonic acid

First results of a 3-cm (9.7 GHz) and 2-mm (140 GHz) waveband EPR study on the magnetic and electron-transport properties over a wide temperature range are reported for the crystalline phase of polyaniline highly doped with p-toluenesulfonic acid. The nature of charge carriers was analyzed and the mechanism of charge transport was established. The spin-lattice and spin-spin relaxation times were measured using the continuous saturation technique. Quasi-three-dimensional (Q3D) domains with a high conductivity are formed in polyaniline by doping. The effective electric conductivity of the polymer is determined by Mott Q3D hopping in domains of this type and Q1D variable-range hopping between these domains. There is no correlation between charge transport and spin relaxation processes

Charge transport in polyaniline heavily doped with p-toluenesulfonic acid

First results of a 3-cm (9.7 GHz) and 2-mm (140 GHz) waveband EPR study of the magnetic and electron-transport properties over a wide temperature range are reported for the crystalline phase of polyaniline highly doped with p-toluenesulfonic acid. The nature of charge carriers was analyzed and the mechanism of charge transport was established. The spin-lattice and spin-spin relaxation times were measured using the continuous saturation technique. Quasi-three-dimensional (Q3D) domains with a high conductivity are formed in polyaniline by doping. The effective electric conductivity of the polymer is determined by Mott Q3D hopping in domains of this type and Q1D variable-range hopping between these domains. There is no correlation between charge transport and spin relaxation processes. Copyright © 2005 by Pleiades Publishing, Inc

Charge transport in polyaniline heavily doped with p-toluenesulfonic acid

First results of a 3-cm (9.7 GHz) and 2-mm (140 GHz) waveband EPR study on the magnetic and electron-transport properties over a wide temperature range are reported for the crystalline phase of polyaniline highly doped with p-toluenesulfonic acid. The nature of charge carriers was analyzed and the mechanism of charge transport was established. The spin-lattice and spin-spin relaxation times were measured using the continuous saturation technique. Quasi-three-dimensional (Q3D) domains with a high conductivity are formed in polyaniline by doping. The effective electric conductivity of the polymer is determined by Mott Q3D hopping in domains of this type and Q1D variable-range hopping between these domains. There is no correlation between charge transport and spin relaxation processes