![]() Landau level fan diagram analysis of the SdH oscillations gives a finite Berry phase of 0.90π ± 0.16 pointing out Dirac dispersion of massless Dirac fermions and the presence of topologically protected surface states. The high magnetic field magneto-transport data shows SdH oscillations and reveal the presence of 2D Fermi surface with Fermi vector (k F ∼ 0.0568 Å −1) in the DPB thin film that survive up to 10 K. The estimated l ϕ varies with the temperature T as per the power-law ( l ϕ ~ T −0.46), demonstrating the presence of 2D surface states. The WAL is sensitive only to perpendicular magnetic field component and is described well by HLN model. We highlight the observations of WAL and SdH oscillations arising from the surface states in the magneto-transport data obtained on the DPB thin films. In this work we report our results on DPB thin films (~15–20 nm thicknesses) grown on single crystal MgO (100) substrates. 10, it is theoretically predicted that one can drive YPdBi (6.625 Å, which also sits at the border line), from trivial state to topological state by applying tensile strain in its lattice constant. Also in an earlier work done by Chadov et al. DPB (6.63 Å) was predicted to exist at the border between trivial and topological state. Rare earth (R) based RPdBi half Heusler alloys were predicted to exist in either trivial or topological state depending on their equilibrium lattice constant value in a recent work done by Nakajima et al. Band gap of these alloys can be tuned in wide range from 4 eV (e.g., LiMgN) down to zero(e.g., ScPtBi), by choosing X, Y, Z with varying electronegativity and lattice constant values 13. If sum is equal to 8 or 18 electrons, they show semiconductor properties just like classical semiconductors, such as GaAs. 13 have shown that the electronic properties of Half Heusler alloys can be predicted by counting the sum of valence electrons of constituent elements. The crucial ingredient in these intermetallics is the presence of strong spin-orbit coupling (SOC) heavy metal that gives rise to an additional requirement (band inversion) to drive these systems into a topological phase. The X and Y are transition or rare-earth elements and Z is a heavy metal. #WEAK ANTILOCALIZATION AND PHASE COHERENCE FULL#Half-Heusler compounds form a vast group of cubic ternary intermetallic alloys that crystallize in MgAgAs-type structure with composition XYZ that are derived from cubic full Heusler alloys ( X 2 YZ) named after their discoverer, Fritz Heusler 12. Very recently, a number of ternary half-Heusler compounds have been theoretically predicted by several research groups to be candidates for 3D TIs 9, 10, 11. Currently the most extensively studied materials are HgTe/CdTe quantum wells and (Bi/Sb) 2(Te/Se) 3 based 3D TIs 5, 6, 7, 8. These surface/edge helical states are protected by time-reversal-symmetry 2, 3 induced by a strong spin-orbit coupling 4, 5. The topological insulator (TI) is a new quantum state of matter where insulating bulk states coexist with topologically protected spin polarized surface (edge) states in 3D (2D) TI 1. These findings demonstrate that the half Heusler DPB thin films (~15–20 nm) can be used as a suitable material for investigating the novel intrinsic quantum transport properties of surface Dirac fermions. Sheet Carrier density, n s ~ 2.56 × 10 12 cm −2, calculated from the SdH oscillations ( f SdH ~ 106 T) and Hall measurements agree well with each other. This analysis shows a finite Berry phase of 0.90π ± 0.16, reasonably close to the expected π value. The Dirac nature of the surface states is further confirmed by Landau-level fan diagram analysis of SdH oscillations of the magneto-transport data. The power law variation of l ϕ (~T −0.46) indicates the presence of the 2D surface states in DPB film. The measured WAL effect follows the Hikami-Larkin-Nagaoka (HLN) model and the extracted values of phase coherence length ( l ϕ) and α are ~420 nm and ~−0.52 respectively. The films prepared by pulsed laser deposition technique under the optimized conditions, showed a textured structure with (110) planes parallel to the (100) plane of MgO. In this work, we report the observation of a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hall-marks of topological surface states, and Shubnikov-de Hass (SdH) quantum oscillations in oriented DyPdBi (DPB) thin films grown on MgO (100) substrates. The present study develops a general framework for weak antilocalization (WAL) in a three-dimensional (3D) system, which can be applied for a consistent description of longitudinal resistivity \(\rho_ \left( B \right)\) measurements were carried out using a cryogen-free magnet system (Cryogenic Inc.Recently, a number of ternary half-Heusler compounds have been predicted independently by several research groups as candidates for 3D topological insulators. ![]()
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