• S Das

Articles written in Bulletin of Materials Science

• Superconducting gap function and upper critical field in the presence of inhomogeneous magnetic order

Rare earth ternary superconductors are known to exhibit oscillatory magnetic orders below their superconducting transition temperatures. The study of behaviour of superconducting electrons in an inhomogeneous magnetic field is therefore important for such systems. We report here the results of our theoretical study of superconducting gap function Δ(T) and upper critical fieldHc2(T). The results are applied to analyse and explain the variation of Δ(T) andHc2(T) in case of NdRh4B4.

• Electrical conductivity and luminescence of 9-chloro-10,10′-bis-(dichloromethyleno)-(9′H)-10,10′-dihydro-9,9′-bianthryl (CDDB)

The absorption and fluorescenc of 9-chloro-10,10′-bis-(dichloromethyleno)-(9′H)-10,10′-dihydro-9,9′-bianthryl (CDDB) has been studied in polar and nonpolar solvents and also in microcrystal. In polar solvents CDDB emits from two molecular forms, the normal charge transfer form (locally excited, LE form) and the solvent-induced twisted intramolecular charge transfer (TICT) form. Electrically, CDDB possesses semiconducting property with conductivity approximately 10−9 S cm−1 and this conductivity further increases to 10−7 S cm−1 on photoexcitation. Intramolecular charge transfer by hopping mechanism is assumed to be the main process for controlling activation energy and electronic conduction.

• De-stabilization of charge-order state through in-homogeneity in random ionic distribution in the particles of polycrystalline Eu$_{0.2}$La$_{0.3}$Sr$_{0.2}$Ca$_{0.3}$MnO$_3$ sample

In this study the perovskite manganite Eu$_{0.2}$La$_{0.3}$Sr$_{0.2}$Ca$_{0.3}$MnO$_{3}$ batch integrated sample is studied, with special modification done to introduce localized structural strain without micro-level (grains) modification. This consequence successfully generates opposite nature of high orthorhombic strain along b-axis in these samples, although the general structure is same for both with $Pnma$ space group. The sharp magnetic transitions (both Curie temperature and charge-ordertransition) are reported to be mixed in presence of random ionic distribution in its structure. The diffused insulator-metal behaviour, de-stabilization of magnetic state and phase transitions associated with inherent anisotropic strain is discussed and is explained based on chemical disorder-induced structural strain in the present system.

• Experimental and simulation study of charge transport mechanism in HfTiO$_x$ high-k gate dielectric on SiGe heterolayers

Thin HfTiO$_x$ high-k gate dielectric (Ti ${\sim}$26.6%) has been sputter-deposited on strained Si$_{0.81}$Ge$_{0.19}$ heterolayers. The energy band discontinuities and interface properties were studied using X-ray photoelectron spectroscopy. The conduction band offset, and valance band offset between HfTiO$_x$ and Si$_{0.81}$Ge$_{0.19}$ were found to be 1.34 and 2.52 eV, respectively. Further, temperature-dependent (300–500 K) current density–voltage measurements (J–V) were utilized to explore the underlying leakage current conduction mechanism. The conductive dislocation and emission barrier heights at the hetero-interface have also been extracted from temperature-dependent J–V measurement. The barrier height of 1.22 to 2.02 eV for Schottky emission and 0.76 to 1.26 eV for Poole–Frenkel emission were estimated at the heterointerface. To better understand the conduction mechanism between the hetero-interface and temperature-dependent J–V, a calibrated TCAD simulation was carried out.

• # Bulletin of Materials Science

Volume 45, 2022
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020