Disorder-induced Room Temperature Ferromagnetism in Glassy Chromites

[[abstract]]We report an unusual robust ferromagnetic order above room temperature upon amorphization of perovskite [YCrO3] in pulsed laser deposited thin films. This is contrary to the usual expected formation of a spin glass magnetic state in the resulting disordered structure. To understand the underlying physics of this phenomenon, we combine advanced spectroscopic techniques and first-principles calculations. We find that the observed order-disorder transformation is accompanied by an insulator-metal transition arising from a wide distribution of Cr-O-Cr bond angles and the consequent metallization through free carriers. Similar results also found in YbCrO3-films suggest that the observed phenomenon is more general and should, in principle, apply to a wider range of oxide systems. The ability to tailor ferromagnetic order above room temperature in oxide materials opens up many possibilities for novel technological applications of this counter intuitive effect.[[journaltype]]國外[[incitationindex]]SCI[[booktype]]電子版[[countrycodes]]GB

Effect of ozone on the stability of solution-processed anthradithiophene- based organic field-effect transistors

We have investigated the degradation effects of ozone exposure on organic field-effect transistors based on 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene as the organic semiconducting channel layer, as well as on thin films of this widely used, high-mobility, small molecule semi-conductor. Electrical I−V measurements showed a loss of transistor characteristic behavior. We present 1 H Nuclear Magnetic Resonance (NMR) spectroscopy results as well as X-ray Photoemission Spectroscopy (XPS) and Fourier Transform Infrared (FTIR) spectroscopy measurements showing the oxidation of the parent molecule, from which we suggest various possible reaction paths.This is the author accepted manuscript. The final publication of this article (Nasrallah, I. et al "Effect of Ozone on the Stability of Solution-Processed Anthradithiophene-Based Organic Field-Effect Transistors" Chem. Mater., 2014, 26 (13), pp 3914–3919 DOI: 10.1021/cm501397y) can be found on the publisher's website at: http://pubs.acs.org/doi/abs/10.1021/cm501397y Copyright © 2014 American Chemical Societ

Printed 5-V organic operational amplifiers for various signal processing

The important concept of printable functional materials is about to cause a paradigm shift that we will be able to fabricate electronic devices by printing methods in air at room temperature. One of the promising applications of the printed electronics is a disposable electronic patch sensing system which can monitor the health conditions without any restraint. Operational amplifiers (OPAs) are an essential component for such sensing system, since an OPA enables a wide variety of signal processing. Here we demonstrate printed OPAs based on complementary organic semiconductor technology. They can be operated with a standard safe power source of 5 V with a minimal power consumption of 150 nW, and used as amplifiers, a variety of mathematical operators, signal converters, and oscillators. The printed micropower organic OPAs with the low voltage operation and the high versatility will open up the disposable electronic patch sensing system in near future