Question

what do the shubnikov-de hass oscillations describe? draw the magnetoresistance

Answer 1

The observation of a large linear magnetoresistance (MR) and Shubnikov-de Hass (SdH) quantum oscillations in single crystals of YPdBi Heusler topological insulators is found. Owning to the successfully obtained the high-quality YPdBi single crystals, large non-saturating linear MR of as high as 350% at 5K and over 120% at 300 K under a moderate magnetic field of 7 T is observed.
In addition to the large, field-linear MR, the samples exhibit pronounced SdH quantum oscillations at low temperature. Analysis of the SdH data manifests that the high-mobility bulk electron carriers dominate the magnetotransport and are responsible for the observed large linear MR in YPdBi crystals. These findings imply that the Heusler-based topological insulators have superiorities for investigating the novel quantum transport properties and developing the potential
applications.

Materials exhibiting large linear magnetoresistance (MR) have attracted intense research interest due to their potential applications in magnetic random access memory and magnetic sensors. The MR of non-magnetic metals with open Fermi surfaces (e.g., Au) can be linear and non-saturating at high fields. Large linear MR effects have recently been explored in materials with approximately zero bandgaps, such as doped silver chalcogenides, single-crystal bismuth thin films, indium antimonide, and multi-layer graphene,. There are two prevailing models that explain the origin of linear MR behaviors. One is the quantum model by Abrikosov  for materials with gapless linear dispersion spectra and the other is the classical model by Parish and Littlewood
(PL model) for strongly inhomogeneous systems. The recent discoveries of giant linear MR in Bi2Se3 and Bi2Te3 topological insulators (TIs) has brought renewed interest to linear MR.
Because of their unusual surface states that are naturally zero bandgap with linear dispersion, TIs provide a perfect platform on which to study the origin of linear MR. Because some Heusler compounds have recently been predicted to be TIs, it is worth investigating whether large
linear MR can also be observed in Heusler alloys. Considerable efforts have been devoted to the study of the electric structures and transport properties of a number of Heusler-based TIs.
X-ray photoelectron spectroscopy results have shown that such Heusler-based materials as YPtSb, LaPtBi, LuPtSb and LuPdBi are gapless semiconductors with very high mobility although large linear MR and desired Shubnikov-de Haas (SdH) quantum oscillations have not been
observed experimentally in these materials. Among these predicted Heusler TIs is YPdBi, which stands the border between the trivial and topological insulator states. Here, we present experimental evidence demonstrating the existence of large linear MR and the first observation of SdH quantum oscillations in high-quality single crystals of YPdBi.

The MR is about 350% and 120% at 5 and 300 K, respectively, under a magnetic field of 7 T. Analysis of temperature- and angle-dependence of SdH oscillations manifest that the observed large linear MR features do not come from the surface states, but arise from the high-mobility 3D bulk electron carriers in YPdBi crystals.