Recent observations of negative longitudinal magnetoresistance in semimetal

Xu, Xitong; Jia, Shuang

doi:10.1088/1674-1056/25/11/117204

Cited by 14 publications

(8 citation statements)

References 85 publications

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“…2 (a) shows the isothermal MR curves covering over 90 • , the measurement configuration is illustrated as the inset, both B and I are parallel to the 011 direction at θ = 0 • . The MR reaches 120% at 14 T, 350 mK, and θ ∼90 • , about 2 times larger than reported values for CoSi [17], although it is at least one order of magnitude smaller than the huge transverse MR reported for other Dirac and Weyl semimetals [22]. The MR versus tilt angle at selected magnetic fields is plotted in Fig.…”

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confidence: 73%

Single Crystal Growth and Magnetoresistivity of Topological Semimetal CoSi*

Wu¹,

Mi²,

Li³

et al. 2019

Chinese Phys. Lett.

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We report single crystal growth of CoSi, which has recently been recognized as a new type of topological semimetal hosting fourfold and sixfold degenerate nodes. The Shubnikov-de Haas quantum oscillation (QO) is observed on our crystals. There are two frequencies originating from almost isotropic bulk electron Fermi surfaces, in accordance with band structure calculations. The effective mass, scattering rate, and QO phase difference of the two frequencies are extracted and discussed.CoSi is a long known material with FeSi-type cubic structure (B20, space group P2 1 3), of which the thermoelectric property and application have been the focus of study [1,2], it is generally regarded as a semimetal. With the development of characterizing materials by the topology of their electronic band structure, it has recently been suggested that in crystalline systems, in addition to Dirac, Weyl, and nodal line semimetals, band crossing points (nodes) with three-, six-, or eight-fold degeneracies can be stablized [3], the low energy fermionic excitations close to the nodes are called "new fermions". For CoSi and isostructural transition metal silicides RhSi, RhGe, and CoGe, the crystal structure is asymmorphic with threefold rotation symmetry and twofold screw symmetry. Theoretical studies [4,5] found that with inclusion of spin-orbit-coupling (SOC), close to the Fermi level there only exist bands containing a fourfold degenerate node at the Brillouin zone (BZ) center Γ, and a sixfold degenerate node at BZ corner R, both are chiral, thus could serve as a model system in the study of unconventional chiral fermions. Besides, the phonon spectra of these monosilicides host double Weyl points [6]. Subsequent angle resolved photoemission spectrescopy (ARPES) measurements[7-9] have confirmed the overall bulk band structure and the existence of surface Fermi arcs. However, it has been noted that for CoSi preparation of a flat surface for ARPES is at least challenging. Therefore other probes of its bulk electronic structure are needed. At the same time, in the context of searching for feature characteristic of chiral fermions, the physical properties of CoSi are also worth revisiting on high quality single crystalline samples.In this work, we report single crystal growth by the flux method, different from the Czochralski, Bridgman, or chemical vapor transport techniques previously used. The resulting crystals are of decent quality. To our knowledge, this is the first time SdH is observed in CoSi. The angular dependence of the QO frequencies reveals that they are from the bulk electron Fermi surface centered at R in BZ, agreeing with band calculation and * gli@iphy.ac.cn † jlluo@iphy.ac.cn ARPES data. Thus, it is a good starting point for further investigations.The single crystal growth starts with Co powder (99.999%, Alfa), Si powder (99.999%, Alfa), and Sn grains (99.99%), which were mixed with a molar ratio of 1:1:20, loaded into an alumina crucible, then sealed with a partial Ar pressure inside a silica capsule. The reactant was quic...

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confidence: 73%

Single Crystal Growth and Magnetoresistivity of Topological Semimetal CoSi*

Wu¹,

Mi²,

Li³

et al. 2019

Chinese Phys. Lett.

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“…The negative MR survives up to 5 K (in some devices the negative MR is persistent around 10 K, see SI section 5) above which the positive MR starts to be dominant due to the increase of the thermal-related scatterings . Note that the dips in the small magnetic regime (| B | < 0.5 T ) in Figure d are due to the WAL effect originating from the strong spin-obit coupling in WTe 2 . , The negative MR at | B | > 2 T can hardly be explained by the WL effect because of the large corresponding magnetic field range. − As we discuss later, during our experiments we did observe the gate-induced WL behavior in thin samples in a small magnetic regime which is distinct from the nonsaturation negative MR at ±9 T in Figure c. We then try to explore other origins of the negative MR in WTe 2 .…”

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confidence: 90%

Tunable Positive to Negative Magnetoresistance in Atomically Thin WTe₂

et al. 2017

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Transitional metal ditelluride WTe has been extensively studied owing to its intriguing physical properties like nonsaturating positive magnetoresistance and being possibly a type-II Weyl semimetal. While surging research activities were devoted to the understanding of its bulk properties, it remains a substantial challenge to explore the pristine physics in atomically thin WTe. Here, we report a successful synthesis of mono- to few-layer WTe via chemical vapor deposition. Using atomically thin WTe nanosheets, we discover a previously inaccessible ambipolar behavior that enables the tunability of magnetoconductance of few-layer WTe from weak antilocalization to weak localization, revealing a strong electrical field modulation of the spin-orbit interaction under perpendicular magnetic field. These appealing physical properties unveiled in this study clearly identify WTe as a promising platform for exotic electronic and spintronic device applications.

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“…In this sense, the static CME has been observed via magnetotransport measurements in [35][36][37][38] (see Ref. [39,40] for further references and review of recent results), and via non-local voltage measurements in [41].…”

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Dynamic Chiral Magnetic Effect and Faraday Rotation in Macroscopically Disordered Helical Metals

Pesin

2017

Phys. Rev. Lett.

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We develop an effective medium theory for electromagnetic wave propagation through gapless nonuniform systems with dynamic chiral magnetic effect. The theory allows to calculate macroscopicdisorder-induced corrections to the values of optical, as well as chiral magnetic conductivities. In particular, we show that spatial fluctuations of optical conductivity induce corrections to the effective value of the chiral magnetic conductivity. Experimentally, these corrections can be observed as sharp features in the Faraday rotation angle near frequencies that correspond to the bulk plasmon resonances of a material. Such features are not expected to be present in single crystal samples.

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Recent observations of negative longitudinal magnetoresistance in semimetal

Cited by 14 publications

References 85 publications

Single Crystal Growth and Magnetoresistivity of Topological Semimetal CoSi*

Single Crystal Growth and Magnetoresistivity of Topological Semimetal CoSi*

Tunable Positive to Negative Magnetoresistance in Atomically Thin WTe₂

Dynamic Chiral Magnetic Effect and Faraday Rotation in Macroscopically Disordered Helical Metals

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Recent observations of negative longitudinal magnetoresistance in semimetal

Cited by 14 publications

References 85 publications

Single Crystal Growth and Magnetoresistivity of Topological Semimetal CoSi*

Single Crystal Growth and Magnetoresistivity of Topological Semimetal CoSi*

Tunable Positive to Negative Magnetoresistance in Atomically Thin WTe2

Dynamic Chiral Magnetic Effect and Faraday Rotation in Macroscopically Disordered Helical Metals

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Tunable Positive to Negative Magnetoresistance in Atomically Thin WTe₂