Multiple mechanisms for extremely large magnetoresistance (XMR) found in many topologically nontrivial/trivial semimetals have been theoretically proposed, but experimentally it is unclear which mechanism is responsible in a particular sample. In this article, by the combination of band structure calculations, numerical simulations of magnetoresistance (MR), Hall resistivity and de Haas-van Alphen (dHvA) oscillation measurements, we studied the MR anisotropy of SiP$_{2}$ which is verified to be a topologically trivial, incomplete compensation semimetal. It was found that as magnetic field, $H$, is applied along the $a$ axis, the MR exhibits an unsaturated nearly linear $H$ dependence, which was argued to arise from incomplete carriers compensation. For the $H$ $\parallel$ [101] orientation, an unsaturated nearly quadratic $H$ dependence of MR up to 5.88 $\times$ 10$^{4}$$\%$ (at 1.8 K, 31.2 T) and field-induced up-turn behavior in resistivity were observed, which was suggested due to the existence of hole open orbits extending along the $k_{x}$ direction. Good agreement of the experimental results with the simulations based on the calculated Fermi surface (FS) indicates that the topology of FS plays an important role in its MR.
Three-dimensional (3D) Dirac semimetals are new quantum materials and can be viewed as 3D analogues of graphene. Many fascinating electronic properties have been proposed and realized in 3D Dirac semimetals, which demonstrates their potential applications in next generation quantum devices. Bismuth-antimony Bi1-xSbx can be tuned from a topological insulator to a band insulator through a quantum critical point at x ~ 4%, where 3D Dirac fermions appear. Here, we report on a magnetotransport study of Bi1-xSbx at such a quantum critical point. An unusual magnetic-field induced semimetal-semiconduc…
Magnetic topological semimetals, the latest member of topological quantum materials, are attracting extensive attention as they may lead to topologically-driven spintronics. Currently, magnetotransport investigations on these materials are focused on anomalous Hall effect. Here, we report on the magnetoresistance anisotropy of topological semimetal CeBi, which has tunable magnetic structures arising from localized Ce 4f electrons and exhibits both negative and positive magnetoresistances, depending on the temperature. We found that the angle dependence of the negative magnetoresistance, regard…
Non-stoichiometry effect on the extreme magnetoresistance is systematically investigated for the Weyl semimetal WTe2. Magnetoresistance and Hall resistivity are measured for the as-grown samples with a slight difference in Te vacancies and the annealed samples with increased Te vacancies. The fittings to a two-carrier model show that the magnetoresistance is strongly dependent on the residual resistivity ratio (i.e., the degree of non-stoichiometry), which is eventually understood in terms of electron doping which not only breaks the balance between electron-type and hole-type carrier densitie…
We report the magnetoresistance of ScSb, which is a semimetal with a simple rocksalt-type structure. We found that the magnetoresistance reaches $\sim$28000 % at 2 K and 14 T in our best sample, and it exhibits a resistivity plateau at low temperatures. The Shubnikov-de Haas oscillations extracted from the magnetoresistance data allow the full construction of the Fermi surface, including the so-called $α_3$ pocket which has been missing in other closely related monoantimonides, and an additional hole pocket centered at $Γ$. The electron concentration ($n$) and the hole concentration ($p$) are …
Discovery of Weyl fermions in semimetallic tansition-metal monopnictides is a major breakthrough in condensed matter physics. A Weyl semimetal is characterized by the existence of robust Weyl points and unclosed topological surface states in the form of Fermi arc. All the four compounds of the Weyl semimetal transition monopnictide family i.e. NbP, TaP, NbAs and TaAs exhibit extremely high mobility and unsaturated high magnetoresistance (MR). For example, MR values are 8.5x10^5% at 1.85 K for NbP and 1.5x10^5% at 3 K in 9 T for TaAs. NbP also achieves very low value of residual resistivity 0.6…
Magnetic field effect on linear and nonlinear conductivity in a quasi-one-dimensional Weyl semimetal with a charge density wave (CDW) (TaSe$_4$)$_2$I is studied. Longitudinal magnetoresistance in all known regimes of CDW motion (linear conduction, creep, sliding, "Fröhlich superconductivity") is small, positive and do not exceed a fraction of per cent. Similar magnetotransport measurements were performed in samples profiled by focused ion beams is such a way that motion of the CDW in them is accompanied by phase slip of the CDW. In such samples, a peak-like non-parabolic negative magnetoresist…
Recent experiments have revealed spectacular transport properties of conceptually simple semimetals. For example, normal semimetals (e.g. WTe$_2$) have started a new trend to realize a large magnetoresistance, which is the change of electrical resistance by an external magnetic field. Weyl semimetal (WSM) is a topological semimetal with massless relativistic electrons as the three-dimensional analogue of graphene and promises exotic transport properties and surface states, which are different from those of the famous topological insulators (TIs). In this letter, we choose to utilize NbP in mag…
Electron-hole (e-h) compensation is a hallmark of multi-band semimetals with extremely large magnetoresistance (XMR) and has been considered to be the basis for XMR. Recent spectroscopic experiments, however, reveal that YSb with non-saturating magnetoresistance is uncompensated, questioning the e-h compensation scenario for XMR. Here we demonstrate with magnetoresistivity and angle dependent Shubnikov - de Haas (SdH) quantum oscillation measurements that YSb does have nearly perfect e-h compensation, with a density ratio of $0.95$ for electrons and holes. The density and mobility anisotropy o…
We report large magnetoresistance (MR) at low temperatures in single-crystalline nonmagnetic compounds TaAs$_2$ and NbAs$_2$. Both compounds exhibit parabolic-field-dependent MR larger than $5\times10^3$ in a magnetic field of 9 Tesla at 2 K. The MR starts to deviate from parabolic dependence above 10 T and intends to be saturated in 45 T for TaAs$_2$ at 4.2 K. The Hall resistance measurements and band structural calculations reveal their compensated semimetal characteristics. The large MR at low temperatures is ascribed to a resonance effect of the balanced electrons and holes with large mobi…
The topological semimetal $β$-Ag2Se features a Kramers Weyl node at the origin in momentum space and a quadruplet of spinless Weyl nodes, which are annihilated by spin-orbit coupling. We show that single crystalline $β$-Ag2Se manifests giant Shubnikov-de Haas oscillations in the longitudinal magnetoresistance which stem from a small electron pocket that can be driven beyond the quantum limit by a field less than 9 T. This small electron pocket is a remainder of the spin-orbit annihilatedWeyl nodes and thus encloses a Berry-phase structure. Moreover, we observed a negative longitudinal magnetor…
The extremely stringent requirement on material quality has hindered the investigation and potential applications of exotic chiral magnetic effect in Dirac semimetals. Here, we propose that gray tin is a perfect candidate for observing the chiral anomaly effect and Shubnikov-de-Haas (SdH) oscillation at relatively low magnetic field. Based on effective $k.p$ analysis and first-principles calculations, we discover that gray tin becomes a Dirac semimetal under tensile uniaxial strain, in contrast to a topological insulator under compressive uniaxial strain as known before. In this newly found Di…
The peculiar band structure of semimetals exhibiting Dirac and Weyl crossings can lead to spectacular electronic properties such as large mobilities accompanied by extremely high magnetoresistance. In particular, two closely neighbouring Weyl points of the same chirality are protected from annihilation by structural distortions or defects, thereby significantly reducing the scattering probability between them. Here we present the electronic properties of the transition metal diphosphides, WP2 and MoP2, that are type-II Weyl semimetals with robust Weyl points. We present transport and angle res…
Several early transition metal dipnictides have been found to host topological semimetal states and exhibit large magnetoresistance. In this study, we use angle-resolved photoemission spectroscopy (ARPES) and magneto-transport to study the electronic properties of a new transition metal dipnictide ZrP$_2$. We find that ZrP$_2$ exhibits an extremely large and unsaturated magnetoresistance of up to 40,000 % at 2 K, which originates from an almost perfect electron-hole compensation. Our band structure calculations further show that ZrP$_2$ hosts a topological nodal loop in proximity to the Fermi …
Very strong magnetoresistance and a resistivity plateau impeding low temperature divergence due to insulating bulk are hallmarks of topological insulators and are also present in topological semimetals where the plateau is induced by magnetic field, when time-reversal symmetry (protecting surface states in topological insulators) is broken. Similar features were observed in a simple rock-salt-structure LaSb, leading to a suggestion of the possible non-trivial topology of 2D states in this compound. We show that its sister compound YSb is also characterized by giant magnetoresistance exceeding …
Recently discovered Dirac and Weyl semimetals display unusual magnetoresistance phenomena, including a large, non-saturating, linear transverse magnetoresistance and a negative longitudinal magnetoresistance. The latter is often considered as evidence of fermions having a defined chirality. Classical mechanisms, due to disorder or non-uniform current injection, can however, also produce negative longitudinal magnetoresistance. Here, we report on magnetotransport measurements performed on epitaxial thin films of Cd3As2, a three-dimensional Dirac semimetal. Quasi-linear positive transverse magne…
Half-Heusler compounds have attracted significant attention because of their topologically non-trivial electronic structure, which leads to unusual electron transport properties. We thoroughly investigated the magnetotransport properties of high-quality single crystals of two half-Heusler phases, TbPtBi and HoPtBi, in pursuit of the characteristic features of topologically non-trivial electronic states. Both studied compounds are characterized by the giant values of transverse magnetoresistance with no sign of saturation in magnetic field up to 14 T. HoPtBi demonstrates the Shubnikov-de Haas e…
NbP is a recently realized Weyl semimetal (WSM), hosting Weyl points through which conduction and valence bands cross linearly in the bulk and exotic Fermi arcs appear. However, the most intriguing transport phenomenon of a WSM, the chiral anomaly-induced negative magnetoresistance (NMR) in parallel electric and magnetic fields, has yet to be observed in NbP. In intrinsic NbP the Weyl points lie far from the Fermi energy, making chiral magneto-transport elusive. Here, we use Ga-doping to relocate the Fermi energy in NbP sufficiently close to the Weyl points, for which the different Fermi surfa…
We report the observation of colossal positive magnetoresistance (MR) in single crystalline, high mobility TaAs2 semimetal. The excellent fit of MR by a single quadratic function of the magnetic field B over a wide temperature range (T = 2-300 K) suggests the semiclassical nature of the MR. The measurements of Hall effect and Shubnikov-de Haas oscillations, as well as band structure calculations suggest that the giant MR originates from the nearly perfectly compensated electrons and holes in TaAs2. The quadratic MR can even exceed 1,200,000% at B = 9 T and T = 2 K, which is one of the largest …
Materials with high carrier mobility showing large magnetoresistance (MR) have recently received much attention because of potential applications in future high-performance magneto-electric devices. Here, we report on the discovery of an electron-hole-compensated half-Heusler semimetal LuPtBi that exhibits an extremely high electron mobility of up to 79000 cm2/Vs with a non-saturating positive MR as large as 3200% at 2 K. Remarkably, the mobility at 300 K is found to exceed 10500 cm2/Vs, which is among the highest values reported in three-dimensional bulk materials thus far. The clean Shubniko…
We have performed polarized and temperature-dependent Raman scattering measurements on extremely large magnetoresitance compounds TaAs$_2$ and NbAs$_2$. In both crystals, all the Raman active modes, including six A$_g$ modes and three B$_g$ modes, are clearly observed and well assigned with the combination of symmetry analysis and first-principles calculations. The well-resolved periodic intensity modulations of the observed modes with rotating crystal orientations, verify the symmetry of each assigned mode and are fitted to experimentally determine the elements of Raman tensor matrixes. The b…
We performed calculations of the electronic band structure and the Fermi surface as well as measured the longitudinal resistivity rhoxx(T,H), Hall resistivity rhoxy(T,H) and quantum oscillations of the magnetization as a function of temperature at various magnetic fields for MoO2 with monoclinic crystal structure. The band structure calculations show that MoO2 is a nodal-line semimetal when spin-orbit coupling is ignored. It was found that a large magnetoresistance reaching 5.03x10^4% at 2 K and 9 T, its nearly quadratic field dependence and a field-induced up-turn behavior of rhoxx(T), the ch…
Topological insulators are characterized by an inverted band structure in the bulk and metallic surface states on the surface. In LaBi, a semimetal with a band inversion equivalent to a topological insulator, we observe surface state like behavior in the magnetoresistance. The electrons responsible for this pseudo two dimensional transport, however, originate from the bulk states rather topological surface states, which is witnessed by the angle dependent quantum oscillations of the magnetoresistance and ab initio calculations. As a consequence, the magnetoresistance exhibits strong anisotropy…
Monobismuthides of yttrium and lutetium are shown as new representatives of materials which exhibit extreme magnetoresistance and magnetic-field-induced resistivity plateau. At low temperatures and in magnetic field of 9T the magnetoresistance attains the order of magnitude of 10,000% and 1,000%, on YBi and LuBi, respectively. Our thorough examination of electron transport properties of both compounds show that observed features are the consequence of nearly perfect carrier compensation rather than of possible nontrivial topology of electronic states. The field-induced plateau of electrical re…
The kagome-lattice crystal hosts various intriguing properties including the frustrated magnetism, charge order, topological state, superconductivity and correlated phenomena. To achieve high-performance kagome-lattice compounds for electronic and spintronic applications, careful tuning of the band structure would be desired. Here, the electronic structures of kagome-lattice crystal Ni3In2S2 were investigated by transport measurements, angle-resolved photoemission spectroscopy as well as ab initio calculations. The transport measurements reveal Ni3In2S2 as a compensated semimetal with record-h…
Transition-metal dichalcogenides (WTe$_2$ and MoTe$_2$) have drawn much attention, recently, because of the nonsaturating extremely large magnetoresistance (XMR) observed in these compounds in addition to the predictions of likely type-II Weyl semimetals. Contrary to the topological insulators or Dirac semimetals where XMR is linearly dependent on the field, in WTe$_2$ and MoTe$_2$ the XMR is nonlinearly dependent on the field, suggesting an entirely different mechanism. Electron-hole compensation has been proposed as a mechanism of this nonsaturating XMR in WTe$_2$, while it is yet to be clea…
The semiclassical transport theory is especially powerful for investigating galvanomagnetic effects. Generally, the semiclassical theory is applicable only in weak fields because it does not consider Landau quantization. Herein, we extend the conventional semiclassical theory by considering Landau quantization through the field dependence of carrier density in semimetals. The extended semiclassical theory is applicable even in strong fields, where Landau quantization is noticeable. Using this new approach, we explain the qualitative change in the angular dependence of transverse magnetoresista…
Giant Domain-Wall Hall Magnetoresistance in Magnetic Topological Semimetal
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University（华南师范大学）
Rare-earth monopnictides display rich physical behaviors, featuring most notably spin and orbital orders in their ground state. Here, we grow ErBi single crystal and study its magnetic, thermal and electrical properties. An analysis of the magnetic entropy and magnetization indicates that the weak magnetic anisotropy in ErBi possibly derives from the mixing effect, namely the anisotropic ground state of Er3+ (4f11) mingles with the isotropic excited state through exchange interaction. At low temperature, an extremely large magnetoresistance (~104%) with a parabolic magnetic-field dependence is…
Several prominent transport properties have been identified as key signatures of topologicalmaterials. One is the resistivity plateau at low temperatures as observed in several topological insulators (TIs), another is the negative magnetoresistance (MR) when the applied magnetic field is parallel to the current direction as observed in several topological semimetals (TSMs) including Dirac semimetals (DSMs) and Weyl semimetals (WSMs). Usually, these two exotic phenomena emerge in distinct materials with or without time reversal symmetry (TRS), respectively. Here we report the discovery of a new…
We theoretically investigated the magnetoresistance (MR) and planar Hall effect (PHE) in Weyl semimetals based on the semiclassical Boltzmann theory, focusing on the fine structure of the band dispersion. We identified that the negative longitudinal MR and sign change in the PHE occur because of the negative off-diagonal effective-mass with no topological effects or chiral anomaly physics. Our results highlight the crucial role of the off-diagonal effective-mass, which can cause anomalous galvanomagnetic effects. We propose that the PHE creates a dip in their temperature dependence, which enab…
The recent discovery of extreme magnetoresistance in LaSb introduced lanthanum monopnictides as a new platform to study topological semimetals (TSMs). In this work we report the discovery of extreme magnetoresistance in LaBi, confirming lanthanum monopnictides as a promising family of TSMs. These binary compounds with the simple rock-salt structure are ideal model systems to search for the origin of extreme magnetoresistance. Through a comparative study of magnetotransport effects in LaBi and LaSb, we construct a triangular temperature-field phase diagram that illustrates how a magnetic field …
Negative magnetoresistance is rare in non-magnetic materials. Recently, a negative magnetoresistance has been observed in the quantum limit of $β$-Ag$_2$Se, where only one band of Landau levels is occupied in a strong magnetic field parallel to the applied current. $β$-Ag$_2$Se is a material that host a Kramers Weyl cone with band degeneracy near the Fermi energy. Kramers Weyl cones exist at time-reversal invariant momenta in all symmorphic chiral crystals, and at a subset of these momenta, including the $Γ$ point, in non-symmorphic chiral crystals. Here, we present a theory for the negative m…
SrIrO3, the three-dimensional member of the Ruddlesden-Popper iridates, is a paramagnetic semimetal characterised by a the delicate interplay between spin-orbit coupling and Coulomb repulsion. In this work, we study the anisotropic magnetoresistance (AMR) of SrIrO3 thin films, which is closely linked to spin-orbit coupling and probes correlations between electronic transport, magnetic order and orbital states. We show that the low-temperature negative magnetoresistance is anisotropic with respect to the magnetic field orientation, and its angular dependence reveals the appearance of a fourfold…
We study the zero temperature conductance and magnetoconductance of ballistic \textit{p-n} junctions in Weyl semimetals. Electron transport is mediated by Klein tunneling between \textit{n}- and \textit{p}- regions. The chiral anomaly that is realized in Weyl semimetals plays a crucial role in the magnetoconductance of the junction. With the exception of field orientations where the angle between $\mathbf{B}$ and the junction plane is small, magnetoconductance is positive and linear in $B$ at both weak and strong magnetic fields. In contrast, magnetoconductance in conventional \textit{p-n} jun…
Topological materials with extremely large magnetoresistance exhibit a prognostic feature of resistivity turn-on behaviour. This occurs when the temperature dependence of resistivity changes from metallic to semiconducting characteristics on application of external magnetic field above a threshold value. Here, we study the magneto-transport properties of type-II Weyl Semimetal WP2. We find that semi-classical theories of magnetoresistance are consistent with our data without the need to invoke topological surface states. Our findings in this work provides an alternative basis to understand the…
Controlling the electronic properties via bandstructure engineering is at the heart of modern semiconductor devices. Here, we extend this concept to semimetals where, utilizing LuSb as a model system, we show that quantum confinement lifts carrier compensation and differentially affects the mobility of the electron and hole-like carriers resulting in a strong modification in its large, non-saturating magnetoresistance behavior. Bonding mismatch at the heteroepitaxial interface of a semimetal (LuSb) and a semiconductor (GaSb) leads to the emergence of a novel, two-dimensional, interfacial hole …
We performed comprehensive theoretical and experimental studies of the electronic structure and the Fermi surface topology of two novel quantum materials, MoSi$_2$ and WSi$_2$. The theoretical predictions of the electronic structure in the vicinity of the Fermi level was verified experimentally by thorough analysis of the observed quantum oscillations in both electrical resistivity and magnetostriction. We established that the Fermi surface sheets in MoSi$_2$ and WSi$_2$ consist of 3D dumbbell-shaped hole-like pockets and rosette-shaped electron-like pockets, with nearly equal volumes. Based o…
We report magnetotransport study on type-II Weyl semimetal WP$_2$ single crystals. Magnetoresistance (MR) exhibits a nonsaturating $H^{n}$ field dependence (14,300\% at 2 K and 9 T) whereas systematic violation of Kohler's rule was observed. Quantum oscillations reveal a complex multiband electronic structure. The cyclotron effective mass close to the mass of free electron m$_e$ was observed in quantum oscillations along $b$-axis, while reduced effective mass of about 0.5$m_e$ was observed in $a$-axis quantum oscillations, suggesting Fermi surface anisotropy. Temperature dependence of the resi…
We report the detailed study on transport properties of ZrB2 single crystal, a predicted topological nodal-line semimetal. ZrB2 exhibits extremely large magnetoresistance as well as field-induced resistivity upturn and plateau. These behaviors can be well understood by the two-band model with the perfect electron - hole compensation and high carrier mobilities. More importantly, the electrons with small effective masses and nontrivial Berry phase have significantly high density when compared to those in known topological semimetals. It strongly suggests that ZrB2 hosts Dirac-like nodal-line fe…
The mixed-chalcogenide compound TlBiSSe realizes a three-dimensional (3D) Dirac semimetal state. In clean, low-carrier-density single crystals of this material, we found Shubnikov-de Haas oscillations to signify its 3D Dirac nature. Moreover, we observed very large linear magnetoresistance (MR) approaching 10,000% in 14 T at 1.8 K, which diminishes rapidly above 30 K. Our analysis of the magnetotransport data points to the possibility that the linear MR is fundamentally governed by the Hall field; although such a situation has been predicted for highly-inhomogeneous systems, inhomogeneity does…
Weyl semimetal emerges as a new topologically nontrivial phase of matter, hosting low-energy excitations of massless Weyl fermions. Here, we present a comprehensive study of the type-II Weyl semimetal WP2. Transport studies show a butterfly-like magnetoresistance at low temperature, reflecting the anisotropy of the electron Fermi surfaces. The four-lobed feature gradually evolves into a two-lobed one upon increasing temperature, mainly due to the reduced relative contribution of electron Fermi surfaces compared to hole Fermi surfaces for the magnetoresistance. Moreover, angle-dependent Berry p…
In this paper, we report the intercone transport of Weyl fermions in NbAs with external magnetic field in parallel to electric field, a quantum phenomenon known as the Adler-Bell-Jackiw anomaly. Surprisingly, the resulting negative magnetoresistance (MR) in NbAs shows significant difference from NbP. The observed low-field positive MR dip, which is missing in NbP at low temperatures, indicates that the spin-orbital coupling (SOC) is significantly stronger in NbAs than in the former. The results imply that the contribution of arsenic to SOC in TaAs and NbAs is not negligible.
A giant planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) is observed in TaP, a nonmagnetic Weyl semimetal with ultrahigh mobility. The perpendicular resistivity (i.e., the planar magnetic field applied normal to the current) far exceeds the zero-field resistivity, which thus rules out the possible origin of negative longitudinal magnetoresistance. The giant PHE/AMR is finally attributed to the large anisotropic orbital magnetoresistance that stems from the ultrahigh mobility. Furthermore, the mobility-enhanced current jetting effects are found to strongly deform the line shape …
The transverse magnetoresistance of a nodal line Dirac semi-metal InBi has been studied. It is found that the magnetoresistance is not quadratic. In the region of small magnetic fields $ B\lesssim 0.1$~T, it is characterized by high curvature, in the region of medium magnetic fields it is described by the sum of linear and quadratic contributions, and in the region of large magnetic fields $ B\gtrsim 1$~T, it approaches a quadratic law with a curvature several times smaller its zero field value. A phenomenological equation is proposed that allows to describe the entire dependence of the resist…
Extremely large positive magnetoresistance (XMR) was found in a nonmagnetic semimetal InBi. Using several single crystals with different residual resistivity ratios (RRRs), we revealed that the XMR strongly depended on the RRR (sample quality). Assuming that there were no changes in effective mass m* and carrier concentrations in these single crystals, this dependence was explained by a semiclassical two-carrier model. First-principle calculations including the spin-orbit interactions (SOI) unveiled that InBi had a compensated carrier balance and SOI-induced "hidden" three-dimensional (3D) Dir…
Chiral anomaly induced negative magnetoresistance (NMR) has been widely used as a critical transport evidence on the existence of Weyl fermions in topological semimetals. In this mini review, we discuss the general observation of the NMR phenomena in non-centrosymmetric NbP and NbAs. We show that NMR can be contributed by intrinsic chiral anomaly of Weyl fermions and/or extrinsic effects, such as superimposition of Hall signals, field-dependent inhomogeneous current flow in the bulk, i.e. current jetting, and weak localization (WL) of coexistent trivial carriers. Such WL controlled NMR is heav…
While pyrite-type PtBi2 with face-centered cubic structure has been predicted to be a three-dimensional (3D) Dirac semimetal, experimental study on its physical properties remains absent. Here we report the angular-dependent magnetoresistance (MR) measurements of PtBi2 single-crystal under high magnetic fields. We observed extreme large unsaturated magnetoresistance (XMR) up to 11.2 million percent at T = 1.8 K in a magnetic field of 33 T, which surpasses the previously reported Dirac materials, such as WTe2, LaSb and NbP. The crystals exhibit an ultrahigh mobility and significant Shubnikov-de…
Cd3As2 is a model material of Dirac semimetal with a linear dispersion relation along all three directions in the momentum space. The unique band structure of Cd3As2 makes it with both Dirac and topological properties. It can be driven into a Weyl semimetal by the symmetry breaking or a topological insulator by enhancing the spin-orbit coupling. Here we report the temperature and gate voltage dependent magnetotransport properties of Cd3As2 nanoplates with Fermi level near the Dirac point. The Hall anomaly demonstrates the two-carrier transport accompanied by a transition from n-type to p-type …
