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

Vishal Bhardwaj,Jhuma Sannigrahi,Ratnamala Chatterjee,Vladimir V Khovaylo,Shivangi Srivastava,Niladri Banerjee,Anupam Bhattacharya,Brajesh K Mani

doi:10.1038/s41598-021-86936-2

Abstract

Half-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.

Highlights

Half-Heusler compounds exhibit a remarkable variety of emergent properties such as heavy-fermion behaviour, unconventional superconductivity and magnetism
A narrow full width at half maximum (FWHM) of about ~ 0.19° obtained from the rocking curve (ω − 2θ) scan around (220) plane indicates the high crystallinity and (110) orientation growth of YPdBi thin film
We summarize the conclusions from our measurements and DFT calculations: The weak anti-localization (WAL) in magneto-transport (Fig. 2c) reflected by the cusp in MR at low fields arises from the destructive interference of spin 1⁄2 carrier wave functions with an associated π Berry phase

Summary

Introduction

Half-Heusler compounds exhibit a remarkable variety of emergent properties such as heavy-fermion behaviour, unconventional superconductivity and magnetism. Recent theoretical studies have indicated the possibility to induce non-trivial topological surface states in an otherwise trivial half-Heusler system by strain engineering. 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. A recent theoretical studies have indicated the possibility to engineer non-trivial topological states in an otherwise trivial half-Heusler system by strain engineering While these non-trivial surface states can be detected in ultra-pure samples by angle resolved photoemission spectroscopy and other surface sensitive techniques[10,11,12,13], whereas transport measurements provide a relatively easy way to detect the surface s tates[6,14,15,16,17,18]. We note that Wang et al reported SdH oscillations and large linear MR in (100) YPdBi single crystals, the origin of these oscillations was entirely attributed to the highly mobile 3D bulk electron carriers and no direct evidence of non-triviality was o bserved[27]

Methods

Results

Conclusion