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- Bhardwaj, Vishal, et al.
(författare)
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Observation of surface dominated topological transport in strained semimetallic ErPdBi thin films
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 117:13
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we present experimental observation of surface-dominated transport properties in [110]-oriented strained (∼1.6%) ErPdBi thin films. The resistivity data show typical semi-metallic behavior in the temperature range of 3 K ≤ T ≤ 350 K with a transition from semiconductor- to metal-like behavior below 3 K. The metallic behavior at low temperature disappears entirely in the presence of an external magnetic field >1 T. The weak-antilocalization (WAL) effect is observed in magneto-conductance data in the low magnetic field region and follows the Hikami-Larkin-Nagaoka (HLN) model. HLN fitting estimated single coherent channel, i.e., α ∼-0.51 at 1.9 K, and the phase coherence length (Lφ) shows the Lφ ∼T-0.52 power law dependence on temperature in the range of 1.9 K-10 K, indicating the observation of 2D WAL. Shubnikov-de Haas (SdH) oscillations are observed in magneto-resistance data below 10 K and are fitted to standard Lifhsitz Kosevich theory. Fitting reveals the effective mass of charge carriers ∼0.15 me and a finite Berry phase of 0.86π± 0.16. The sheet carrier concentration and mobility of carriers estimated using SdH data are ns ∼1.35 × 1012 cm-2 and μs = 1210 cm2 V-1 s-1, respectively, and match well with the data measured using the Hall measurement at 1.9 K to be n ∼1.22 × 1012 cm-2, μ = 1035 cm2 V-1 s-1. These findings indicate the non-trivial nature and surface-dominated transport properties of strained (110) ErPdBi thin films at low temperatures.
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- Srivastava, Shivangi, et al.
(författare)
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Enhanced superconductivity originating from f -electron doping in topologically nontrivial YPdBi half-Heusler thin films
- 2024
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Ingår i: Physical Review Materials. - 2475-9953. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- YPdBi is a well-studied diamagnetic topologically trivial half-Heusler alloy that is superconducting with Tc∼1 K. When strained or in thin-film form, it shows a topologically nontrivial surface state with Tc ∼1.25K. ErPdBi is a well-studied topologically nontrivial half Heusler with Tc ∼1.22K. In this work, we demonstrate that the f-electron doping in YPdBi provides a unique way to selectively tune the electronic structure and aid in increasing the superconducting transition temperature of YPdBi. This work presents systematic measurements of electrical resistivity and magnetotransport on half-Heusler thin films of Y(1-x)ErxPdBi (x=0.2, 0.5, and 0.8), prepared using the pulsed laser deposition technique. All the films were observed to be semimetallic, with a sharp downturn in resistivity at low temperatures T < 5 K; the E5 film (Tc∼4.4 K) and E8 film (Tc∼3.7 K) reach a zero-resistivity value, within the experimental limit. The doping of f electron on Y+3 sites possibly gives rise to the improved Fermi parameters and an increase in Tc. Magnetoresistance measurements and first-principle calculations support that Y(1-x)ErxPdBi are topologically nontrivial semimetals. The first-principle calculations also show that with an increase in the doping concentration (x), more f bands start to appear near Fermi level (EF), giving rise to an increase in the band-inversion strength due to s-f exchange interaction. The nontrivial band structure, odd-parity Cooper pair, and noncentrosymmetric crystal structure suggest the presence of unconventional superconductivity in the E5 and E8 films.
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