Strain driven emergence of topological non-triviality in YPdBi thin 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.

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

Physical Chemistry Chemical Physics ◽

10.1039/c4cp04502e ◽

2015 ◽

Vol 17 (5) ◽

pp. 3577-3583 ◽

Cited By ~ 15

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

Scientific Reports ◽

10.1038/s41598-021-91930-9 ◽

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.

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Spin accumulation in topological insulator thin films—influence of bulk and topological surface states

Journal of Physics D Applied Physics ◽

10.1088/1361-6463/aadad7 ◽

2018 ◽

Vol 51 (42) ◽

pp. 425301

Author(s):

Zhuo Bin Siu ◽

Yi Wang ◽

Hyunsoo Yang ◽

Mansoor B A Jalil

Keyword(s):

Thin Films ◽

Topological Insulator ◽

Surface States ◽

Spin Accumulation ◽

Topological Surface

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Three-Dimensional Topological States of Phonons with Tunable Pseudospin Physics

Research ◽

10.34133/2019/5173580 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Yizhou Liu ◽

Yong Xu ◽

Wenhui Duan

Keyword(s):

Degrees Of Freedom ◽

Three Dimensional ◽

Surface States ◽

Phonon Transport ◽

Efficient Control ◽

Topological States ◽

Topological Surface ◽

Symmetry Protected ◽

Energy Information ◽

Crystalline Symmetry

Efficient control of phonons is crucial to energy-information technology, but limited by the lacking of tunable degrees of freedom like charge or spin. Here we suggest to utilize crystalline symmetry-protected pseudospins as new quantum degrees of freedom to manipulate phonons. Remarkably, we reveal a duality between phonon pseudospins and electron spins by presenting Kramers-like degeneracy and pseudospin counterparts of spin-orbit coupling, which lays the foundation for “pseudospin phononics”. Furthermore, we report two types of three-dimensional phononic topological insulators, which give topologically protected, gapless surface states with linear and quadratic band degeneracies, respectively. These topological surface states display unconventional phonon transport behaviors attributed to the unique pseudospin-momentum locking, which are useful for phononic circuits, transistors, antennas, etc. The emerging pseudospin physics offers new opportunities to develop future phononics.

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

10.1117/12.2249587 ◽

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

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

Applied Physics Letters ◽

10.1063/1.4884348 ◽

2014 ◽

Vol 104 (24) ◽

pp. 241606 ◽

Cited By ~ 21

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

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Study the Conduction Mechanism and the Electrical Response of Strained Nano-thin 3C-SiC Films on Si used as Surface Sensors

MRS Proceedings ◽

10.1557/proc-1129-v04-20 ◽

2008 ◽

Vol 1129 ◽

Author(s):

Ronak Rahimi ◽

Christopher M Miller ◽

Alan Munger ◽

Srikanth Raghavan ◽

C D Stinespring ◽

...

Keyword(s):

Thin Films ◽

Bulk Material ◽

Electrical Response ◽

Surface States ◽

High Energy ◽

Mems Devices ◽

Hydrogen Flow ◽

Metal Semiconductor Metal ◽

Strained Films ◽

Sic Films

AbstractVarious superior properties of SiC such as high thermal conductivity, chemical and thermal stability and mechanical robustness provide the basis for electronic and MEMS devices of novel design [1]. This work evaluates heterostructures that consist of a few nanometers-thick 3C-SiC films on silicon substrates. Nano-thin SiC films differ significantly in their electrical behavior compared to the bulk material [2], a finding that gives rise to a potential use of these films as surface sensors. To gain a better understanding of the effect of surface states on the electrical response of these thin, strained films, several metal-semiconductor-metal heterostructures have been examined under variable conditions. The nano-thin, strained films were grown using gas source molecular beam epitaxy. Reflection high-energy electron diffraction patterns obtained from several 3C-SiC films indicate that these films are strained nearly 3% relative to the SiC lattice constant. Al, Cr and Pt contacts to a nano-thin film 3C-SiC were deposited and characterized. I-V measurements of the strained nano-thin films demonstrate metal-semiconductor-metal characteristics. Band offsets due to biaxial tensile strain introduced within the 3C-SiC films were calculated and band diagrams incorporating strain effects were simulated. Electron affinity of 3C-SiC has been extracted from experimental I-V curves and is in good agreement with the value that has been calculated for a strained 3C-SiC film [3]. On the basis of experimental and simulation results, an empirical model for the current transport has been proposed. Fabricated devices have been characterized in a controlled environment under hydrogen flow and also in a reactive ambient, while heating the sample and oxidizing the surface, to investigate the effects of the environment on the surface states. Observed changes in I-V characteristics suggest that these nano-thin films can be used as surface sensors.

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