544 research outputs found
Linear and Nonlinear Optical Properties of Mn doped Benzimidazole Thin Films
In the present work, the Mn doped benzimidazole (BMZ) thin films were
prepared by simple chemical bath deposition technique. The material was
directly deposited as thin film on glass substrates and the metal concentration
in the solution was varied in weight percentage in order to investigate the
dopant effect on the properties of thin films. Similarly, the Mn doped BMZ
films were deposited in different solution temperature to study the effect of
deposition temperature on the properties of thin films. The PXRD and FT-IR
spectroscopy are used to study the structural and the presence of functional
groups in the BMZ medium. Depending upon the solution temperature, thickness of
the films varying from 0.6 to 1.2 {\mu}m and the optical transparency of the
samples increases with the increasing temperature up to 50 {\deg}C. Second
Harmonic Generation (SHG) efficiency of the films is measured for all the
films. Third order nonlinear optical properties of the films were analyzed
using Z-scan technique. The experimental results show that Mn doped BMZ films
exhibits saturation absorption and negative nonlinearity.Comment: This has been presented in DAE 58th Solid State Symposium held at
Thapar University, Patiala, Punjab, India. Will be published in AIP
conference proceedings soo
Structure and composition tunable superconductivity, band topology and elastic response of hard binary niobium nitrides NbN, NbN and NbN
We perform a systematic \textit{ab initio} density functional study of the
superconductivity, electronic and phononic band structures, electron-phonon
coupling and elastic constants of all four possible structures of niobium
nitride -NbN as well as Nb-rich -NbN and N-rich
-NbN. First of all, we find that all four structures of
-NbN are superconductors with superconducting transition
temperatures () ranging from 0.6 K to 6.1 K, depending on the structure.
This explains why previous experiments reported contradicting values for
-NbN. Furthermore, both -NbN and
-NbN are predicted to be superconductors with rather high
of 8.5 K and 15.3 K, respectively. Second, the calculated elastic
constants and phonon dispersion relations show that all the considered niobium
nitride structures are mechanically and dynamically stable. Moreover, the
calculated elastic moduli demonstrate that all the niobium nitrides are hard
materials with bulk moduli and hardness being comparable to or larger than the
well-known hard sapphire. Third, the calculated band structures reveal that the
nitrides possess both type I and type II Dirac nodal points and are thus
topological metals. Finally, the calculated electron-phonon coupling strength,
superconductivity and mechanical property of the niobium nitrides are discussed
in terms of their underlying electronic structures and also Debye temperatures.
The present \textit{ab initio} study thus indicates that -NbN,
-NbN and -NbN are hard superconductors
with nontrivial band topology and are promising materials for exploring exotic
phenomena due to the interplay of hardness, superconductivity and nontrivial
band topology.Comment: 12 pages, 4 tables and 6 figure
- β¦