scholarly journals 2D weak anti-localization in thin films of the topological semimetal Pd$$_{3}$$Bi$$_{2}$$S$$_{2}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shama ◽  
R. K. Gopal ◽  
Goutam Sheet ◽  
Yogesh Singh
Keyword(s):  
Thin Films ◽  
Phonon Scattering ◽  
Surface States ◽  
Relaxation Mechanism ◽  
Transport Studies ◽  
Bulk Carriers ◽  
Topological Semimetal ◽  
Topological Surface ◽  
First Time ◽  
Electron Phonon Scattering

AbstractPd$$_{3}$$ 3 Bi$$_{2}$$ 2 S$$_{2}$$ 2 (PBS) is a recently proposed topological semimetal candidate. However, evidence for topological surface states have not yet been revealed in transport measurements due to the large mobility of bulk carriers. We report the growth and magneto-transport studies of PBS thin films where the mobility of the bulk carriers is reduced by two orders of magnitude, revealing for the first time, contributions from the 2-dimensional (2D) topological surface states in the observation of the 2D weak anti-localization (WAL) effect in magnetic field and angle dependent conductivity measurements. The magnetotransport data is analysed within the 2D Hikami-Larkin-Nagaoka (HLN) theory. The analysis suggests that multiple conduction channels contribute to the transport. It is also found that the temperature dependence of the dephasing length can’t be explained only by electron-electron scattering and that electron-phonon scattering also contributes to the phase relaxation mechanism in PBS films.

scholarly journals Strain driven emergence of topological non-triviality in YPdBi thin films

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vishal Bhardwaj ◽  
Anupam Bhattacharya ◽  
Shivangi Srivastava ◽  
Vladimir V. Khovaylo ◽  
Jhuma Sannigrahi ◽  
...  
Keyword(s):  
Thin Films ◽  
Heavy Fermion ◽  
Critical Role ◽  
Surface States ◽  
Strain Engineering ◽  
Emergent Properties ◽  
Spintronic Devices ◽  
Topological States ◽  
Topological Surface ◽  
Strained Films

AbstractHalf-Heusler compounds exhibit a remarkable variety of emergent properties such as heavy-fermion behaviour, unconventional superconductivity and magnetism. Several of these compounds have been predicted to host topologically non-trivial electronic structures. Remarkably, recent theoretical studies have indicated the possibility to induce non-trivial topological surface states in an otherwise trivial half-Heusler system by strain engineering. Here, using magneto-transport measurements and first principles DFT-based simulations, we demonstrate topological surface states on strained [110] oriented thin films of YPdBi grown on (100) MgO. These topological surface states arise in an otherwise trivial semi-metal purely driven by strain. Furthermore, we observe the onset of superconductivity in these strained films highlighting the possibility of engineering a topological superconducting state. Our results demonstrate the critical role played by strain in engineering novel topological states in thin film systems for developing next-generation spintronic devices.

scholarly journals Modeling of Thermoelectric Properties of Semi-Conductor Thin Films With Quantum and Scattering Effects

2006 ◽  
Vol 129 (4) ◽  
pp. 492-499 ◽  
Author(s):  
A. Bulusu ◽  
D. G. Walker
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Phonon Scattering ◽  
Quantum Effects ◽  
Effect Of Temperature ◽  
Fundamental Parameters ◽  
Scattering Effects ◽  
Electron Phonon Scattering

Several new reduced-scale structures have been proposed to improve thermoelectric properties of materials. In particular, superlattice thin films and wires should decrease the thermal conductivity, due to increased phonon boundary scattering, while increasing the local electron density of states for improved thermopower. The net effect should be increased ZT, the performance metric for thermoelectric structures. Modeling these structures is challenging because quantum effects often have to be combined with noncontinuum effects and because electronic and thermal systems are tightly coupled. The nonequilibrium Green’s function (NEGF) approach, which provides a platform to address both of these difficulties, is used to predict the thermoelectric properties of thin-film structures based on a limited number of fundamental parameters. The model includes quantum effects and electron-phonon scattering. Results indicate a 26–90 % decrease in channel current for the case of near-elastic, phase-breaking, electron-phonon scattering for single phonon energies ranging from 0.2 meV to 60 meV. In addition, the NEGF model is used to assess the effect of temperature on device characteristics of thin-film heterojunctions whose applications include thermoelectric cooling of electronic and optoelectronic systems. Results show the predicted Seebeck coefficient to be similar to measured trends. Although superlattices have been known to show reduced thermal conductivity, results show that the inclusion of scattering effects reduces the electrical conductivity leading to a significant reduction in the power factor (S2σ).

scholarly journals Electron-phonon scattering in topological insulator thin films

2012 ◽  
Vol 85 (3) ◽  
Author(s):  
Sébastien Giraud ◽  
Arijit Kundu ◽  
Reinhold Egger
Keyword(s):  
Thin Films ◽  
Topological Insulator ◽  
Phonon Scattering ◽  
Electron Phonon Scattering

Temperature evolution of topological surface states in Bi2Se3 thin films studied using terahertz spectroscopy

2017 ◽  
Author(s):  
Varun S. Kamboj ◽  
Angadjit Singh ◽  
Harvey E. Beere ◽  
Thorsten Hesjedal ◽  
Crispin H. W. Barnes ◽  
...  
Keyword(s):  
Thin Films ◽  
Terahertz Spectroscopy ◽  
Surface States ◽  
Temperature Evolution ◽  
Topological Surface

scholarly journals Robust topological surface states of Bi2Se3 thin films on amorphous SiO2/Si substrate and a large ambipolar gating effect

2014 ◽  
Vol 104 (24) ◽  
pp. 241606 ◽  
Author(s):  
Namrata Bansal ◽  
Nikesh Koirala ◽  
Matthew Brahlek ◽  
Myung-Geun Han ◽  
Yimei Zhu ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface States ◽  
Si Substrate ◽  
Amorphous Sio2 ◽  
Topological Surface ◽  
Gating Effect

scholarly journals Topological surface states in strained Dirac semimetal thin films

2020 ◽  
Vol 102 (15) ◽  
Author(s):  
Pablo Villar Arribi ◽  
Jian-Xin Zhu ◽  
Timo Schumann ◽  
Susanne Stemmer ◽  
Anton A. Burkov ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface States ◽  
Dirac Semimetal ◽  
Topological Surface

Enhanced Phonon Scattering in Oxide Superlattices to Improve Laser Induced Thermoelectric Voltages

2007 ◽  
Vol 1053 ◽  
Author(s):  
Hanns-Ulrich Habermeier ◽  
Peng Xiang Zhang ◽  
Hui Zhang
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Layered Structure ◽  
Phonon Scattering ◽  
Single Layer ◽  
Multilayer Thin Films ◽  
Maximum Enhancement ◽  
Seebeck Coefficients ◽  
Thermoelectric Voltage ◽  
First Time

AbstractOptimizing the figure of merit for thermoelectric applications, ZT = S2σ2T/κ is currently at the core of materials oriented research in thermoelectricity. Here, one promising approach is to reduce ther thermal conductivity without sacrificing the electrical conductivity. Constructing superlattices of structurally compatible materials is one way to accomplish this goal. We report an enhanced laser induced thermoelectric voltage (LITV) effect observed in (YBa2Cu3O7/La1-xPbxMnO3)n multilayer thin films for the first time. Two groups of multilayer thin films grown on vicinal cut LaAlO3 substrates were prepared by pulsed laser deposition technique. The first group were grown on different substrates vicinal cut at different angles, and were used for checking the mechanism of the induced voltages. The second group samples were made at different period number n and for studying the number dependence of the peak values of LITV. The substrate angle dependence proved that this is a thermoelectric effect [1]. It was found that the LITV signals were enhanced significantly for these multilayer thin films comparing with the single layer ones. It is natural that the conductivity is going to be anisotropic due to the layered structure, and the same holds for the Seebeck coefficients. The enlarged Seebeck anisotropy will lead to higher induced voltages. Another possible reason is the reduced thermal conductivity in the layered structure. The maximum enhancement of LITV signals takes place at period number of 7, which seems in agreement with the prediction of minimum thermal conductivity in superlattices by Simkin and Mahan.

scholarly journals Growth facets of SrIrO3 thin films and single crystals

CrystEngComm ◽  
2019 ◽  
Vol 21 (25) ◽  
pp. 3822-3828
Author(s):  
L. Fruchter ◽  
V. Brouet ◽  
F. Brisset ◽  
H. Moutaabbid ◽  
Y. Klein
Keyword(s):  
Thin Films ◽  
Single Crystals ◽  
Crystallographic Orientation ◽  
Surface States ◽  
Topological Surface

The crystallographic orientation of SrIrO3 surfaces is decisive for the occurrence of topological surface states.

Topological states modulation of Bi and Sb thin films by atomic adsorption

2015 ◽  
Vol 17 (5) ◽  
pp. 3577-3583 ◽  
Author(s):  
Dongchao Wang ◽  
Li Chen ◽  
Hongmei Liu ◽  
Xiaoli Wang ◽  
Guangliang Cui ◽  
...  
Keyword(s):  
Thin Films ◽  
First Principles ◽  
Surface States ◽  
First Principles Calculations ◽  
Atomic Adsorption ◽  
Topological States ◽  
Topological Surface

Based on first-principles calculations, we systematically investigated the topological surface states of Bi and Sb thin films of 1–5 bilayers in (111) orientation without and with H(F) adsorption, respectively.

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