Department of Physics

&ldquo;IIT Jodhpur is committed to impart quality education to facilitate the creation of qualified, competent and responsible human resources to meet the emerging technological challenges of the world. It is working towards creating an equitable learning platform that is positive, accessible and effective in the face of the modern societal and scientific advancements.

Flexibility in curriculum, in all its academic programs, encompassing elements of teaching, research, creativity, innovation and entrepreneurship is the most unique feature of IIT Jodhpur. The Department of Science and Technology (DST), under the National Mission on Cyber Physical Systems, has identified IIT Jodhpur as a Technology &amp; Innovation Hub in the area of Augmented Reality and Virtual Reality. The institute has also been nominated as the coordinator for the Jodhpur City and Knowledge Cluster by the Office of Principal Scientific Adviser, Government of India.

The sprawling 852-acre IIT Jodhpur campus is a majestic tribute to the deep-rooted diverse cultural heritage of the region. The campus is an architectural masterpiece, which is slated to become an international exemplar of sustainability with net-zero energy, and advanced water and waste management strategies.&rdquo;

IIT Jodhpur

We synthesized p-type Zn0.98Li0.02O and Zn0.96Li0.02Ni0.02O nanorods in conjunction with pristine n-type ZnO nanorods, which are further, used in synthesizing ZnO nanorods based homojunction diodes using a simple two-step solution process. The XRD analysis showed that lattice parameters of the doped samples have no significant changes in comparison to pristine ZnO, substantiating uniform doping. The cross-sectional images of the homojunction substantiate the formation of the p-n junction. The UV-Vis spectroscopy measurement showed the lowering of the optical band gap for Zn0.96Li0.02Ni0.02O nanorods. The presence of higher oxygen vacancies in Zn0.96Li0.02Ni0.02O nanorods is noticed in photoluminescence measurements. The acceptor concentration is ∼1.43 × 1018/cm3 for Zn0.96Li0.02Ni0.02O nanorods and is higher with respect to Zn0.98Li0.02O nanorods. We observed large rectification ratio ∼892 with a lower turn-on voltage ∼3.4 V for Zn0.96Li0.02Ni0.02O based homojunction, relatively better than that of Zn0.98Li0.02O based homojunction. © 2019 Elsevier Ltd

World University root node

Superlattices and Microstructures

Improved rectification behaviour in ZnO nanorods homojunction by suppressing Li donor defects using Li-Ni co-doping

Polymer based solid electrolytes (SEs) are envisaged as futuristic components of safer solid state energy devices. But the semi-crystalline nature and slow dynamics of the host polymer matrix are found to hamper the ion transport through the solid polymer network and hence solid state devices are still far beyond the scope of practical application. In this study, we unravel the synergistic roles of Li salt (LiClO4) and two different polymers-polyethylene oxide (PEO) and polydimethyl siloxane (PDMS), in the Li ion transport through their solid blend based electrolyte. A detailed study using dielectric spectroscopy and thermo-mechanical analysis is conducted to understand the tunability of the PEO chain dynamics with LiClO4 and the mechanism of hopping of Li ions by forming ion pairs with oxygen dipoles on the PEO backbone is established. Despite the lack of PDMS's capability to solvate ions and promote ion transport directly, its proper mixing within the PEO host matrix is demonstrated to enhance ion transport due to the influence of PDMS on the segmental dynamics of PEO. A detailed molecular dynamics study supported by experimental validation suggests that even inert polymers can affect the dynamics of the active host matrix and increase ion transport, leading to next generation high ionic conductivity solid matrices, and opens new avenues in designing polymer based transparent electrolytes. © 2019 The Royal Society of Chemistry.

Fulltext

RSC Advances

Mechanistic insight into the improved Li ion conductivity of solid polymer electrolytes

Some of the strongest polymer-based fibers are obtained by processing a nematic solution of poly-p-phenylene terephthalamide (PPTA) in concentrated acid. Molecular dynamics simulations reveal that the lateral density of PPTA chains in the acid solution is inhomogeneous on scales shorter than the persistence length. Hairpin turns, insertions, and other defects are stabilized by chain-chain contacts. These results suggest a mechanism of fiber assembly through coalescence of nanofibrils, and an explanation for the limited strength of PPTA fibers even at high crystallinity. © 2019 American Physical Society.

Physical Review Materials

Aggregation of poly(p -phenylene terephthalamide) chains: Emergence of fiber defects

The interplay between the nonclassical features and the parity-time (PT) symmetry (or its breaking) is studied here by considering a PT-symmetric system consisting of two cavities with gain and loss. The conditions for PT invariance are obtained for this system. The behavior of the average photon number corresponding to the gain and loss modes for different initial states (e.g., vacuum, NOON, coherent, and thermal states) has also been obtained. With the help of the number operators, quantum Zeno and anti-Zeno effects are studied, and the observed behavior is compared in PT-symmetric (PTS) and PT-symmetry-broken (PTSB) regimes. It has been observed that the relative phase of the input coherent fields plays a key role in the occurrence of these effects. Further, some nonclassicality features are witnessed using criteria based on the number operator(s). Specifically, intermodal antibunching, sum, and difference squeezing are investigated for specific input states. It is found that the various nonclassical features, including the observed quantum Zeno and anti-Zeno effects, are suppressed when one goes from the PTS to PTSB regime. In other words, the dominance of the loss or gain rate in the field modes over the coupling strength between them diminishes the nonclassical features of the system. © 2019 American Physical Society.

Physical Review A

Quantum Zeno effect and nonclassicality in a PT-symmetric system of coupled cavities

Gravity induced neutrino-antineutrino oscillations are studied in the context of one- and two-flavor scenarios. This allows one to investigate the particle-antiparticle correlations in two and four level systems, respectively. Flavor entropy is used to probe the entanglement in the system. The well known witnesses of nonclassicality such as Mermin and Svetlichny inequalities are investigated. Since the extent of neutrino-antineutrino oscillation is governed by the strength of the gravitational field, the behavior of nonclassicality shows interesting features as one varies the strength of the gravitational field. Specifically, the suppression of the entanglement with the increase of the gravitational field is observed which is witnessed in the form of decrease in the flavor entropy of the system. The features of the Mermin and the Svetlichny inequalities allow one to make statements about the degeneracy of neutrino mass eigenstates. © 2019 authors.

Physical Review D

Quantum correlations in neutrino oscillations in curved spacetime

Two-dimensional transition metal dichalcogenides show great potential as promising thermoelectric materials due to their lower dimensionality, the unique density of states and quantum confinement of carriers. Here the effects of mechanical strain on the thermoelectric performances of monolayer WS2 have been investigated using density functional theory associated with semiclassical Boltzmann transport theory. The variation of the Seebeck coefficient and band gap with applied strain has followed the same type of trend. For n-type material the relaxation time scaled power factor (S2σ/τ) increases by the application of compressive strain whereas for p-type material it increases with the application of tensile strain due to valley degeneracy. A 77% increase in the power factor has been observed for the n-type material by the application of uniaxial compressive strain. A decrease in lattice thermal conductivity with the increase in temperature causes an almost 40% increase in ZT product under applied uniaxial compressive strain. From the study, it is observed that uniaxial compressive strain is more effective among all types of strain to enhance the thermoelectric performance of monolayer WS2. Such strain induced enhancement of thermoelectric properties in monolayer WS2 could open a new window for the fabrication of high-quality thermoelectric devices. © 2019 The Royal Society of Chemistry.

Strain induced valley degeneracy: A route to the enhancement of thermoelectric properties of monolayer WS2

Bidirectional multiple negative differential resistance (BM-NDR) was observed from a single 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) molecule at room temperature when the device was studied by using density functional theory (DFT) in association with non-equilibrium Green's function (NEGF). The BM-NDR effect was also verified experimentally by studying the scanning tunneling spectra (STS) of single DDQ molecule. The carrier transport in the device occurs mainly through the transmission channel corresponding to the highest occupied molecular orbital (HOMO) of the molecule and a commensurate change in the magnitude of transmission peak was observed at the peak and valley voltages. The reason for the NDR is proposed to be due to the two competing factors involved namely, the reduction of the molecule and the interface resistance between the molecule and the electrodes. The involvement of both the factors is validated from the molecular projected self-consistent Hamiltonian (MPSH) and the local device density of states (LDDOS) of the device at the corresponding peak and valley voltages. © 2019 Elsevier B.V.

Organic Electronics

Bidirectional multiple negative differential resistance (BM-NDR): An interplay between interface resistance and redox reaction

The influence of P on amorphizing ability, as-quenched microstructure, thermo-physical and soft magnetic properties of Fe–rich (i) Fe81B15-xPxSi2Nb1Cu1 (ii) Fe82B14-xPxSi2Nb1Cu1 and (iii) Fe83B13-xPxSi2Nb1Cu1 (x = 0, 2, 4, 6, 8 at%) melt-spun alloys are investigated. The substitution of P improves amorphization of alloys and restricts the formation of hetero-amorphous microstructure for Fe 83 at% ribbons at around (x = 8). The improvement in short range ordering of P containing clusters with varying Fe content has been discussed within the framework of Cluster-Glue atom model and supported by experimental thermal parameters. The optimal P content in Fe-rich alloys in the range of 4 ≤ x ≤ 6 delivered favourable thermal properties of high primary and secondary crystallization onset temperature viz; Tx1, Tx2 and temperature span ΔT between these onsets. The P substitution drastically restricts the precipitation of secondary crystallites with reduced enthalpy of secondary crystallisation (ΔH2) during annealing and favourably assists in attaining maximum magnetic moment during the primary crystallization stage. Moreover, the P substitution (4–8 at%) effects refinement of α-Fe nanocrystallites and promotes low coercivity (Hc &lt; 20 A/m) in nanocomposite alloys. On contrary, the P substitution linearly reduces saturation magnetization (Ms) by weakening ferromagnetic exchange coupling and ferromagnetic dilution. An optimal content of 4 at% P offers favourable combination of low Hc and High Ms in both amorphous and nanocomposite state. © 2019 Elsevier B.V.

Journal of Magnetism and Magnetic Materials

Role of P on amorphization, microstructure, thermo-physical and soft magnetic properties of Fe-rich FeB(P)SiNbCu melt-spun alloys

The substitution of Fe with Co and B with Si is investigated in a series of high induction Fe84B13Nb2Cu1 amorphous alloys. The as-quenched melt-spun alloys are structurally amorphous in wheel side and a mild crystallites alongwith amorphous phase in air side. The alloy with 35 at% Co addition depicts improved thermal stability, saturation induction and coercivity, and the optimal combination of soft magnetic properties is achieved for an extended annealing temperature range. The additional 10 at% Si deteriorates soft magnetic properties. © 2019 Elsevier B.V.