Negative Longitudinal Magnetoresistance in the Density Wave Phase of 
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Juyal, Abhishek; Agarwal, Amit; Mukhopadhyay, Soumik

doi:10.1103/physrevlett.120.096801

Cited by 28 publications

(26 citation statements)

References 42 publications

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“…Recently, a positive magneto-conductance has been observed in the CDW phase of the predicted Weyl semimetal Y2Ir2O7, 40 because of a reduced de-pinning threshold voltage in longitudinal magnetic fields. However, the phason current was found to be independent of B.…”

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confidence: 99%

Axionic charge-density wave in the Weyl semimetal (TaSe4)2I

Gooth¹,

Bradlyn²,

Honnali³

et al. 2019

Nature

215

157

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An axion insulator is a correlated topological phase, predicted to arise from the formation of a charge density wave in a Weyl semimetal. The accompanying sliding mode in the charge density wave phase, the phason, is an axion. It is expected to cause anomalous magneto-electric transport effects. However, this axionic charge density wave has so far eluded experimental detection. In this paper, we report the observation of a large, positive contribution to the magneto-conductance in the sliding mode of the charge density wave Weyl semimetal (TaSe4)2I for collinear electric and magnetic fields (E||B).The positive contribution to the magneto-conductance originates from the anomalous axionic contribution of the chiral anomaly to the phason current, and is locked to the parallel alignment of E and B. By rotating B, we show that the angular dependence of the magneto-conductance is consistent with the anomalous transport of an axionic charge density wave. 3 Axions refer to elementary particles that have long been known in quantum field theory, 1,2 but have yet to be observed in nature. However, it has been recently understood that axions can emerge as collective electronic excitations in certain crystals, so-called axion insulators. 3 Despite being fully gapped to single-particle excitations in the bulk and at the surface, an axion insulator is characterized by an effective action, which includes a topological EB-term, where E and B are the electromagnetic fields inside the insulator, and  plays the role of the dynamical axion field. Physically, the average value of  is determined by the microscopic details of the band structure of the system, and gives rise to unusual magnetoelectric response properties such as quantum anomalous Hall conductivities 4-9 , the quantized circular photo-galvanic 4,10,11 effect, and the chiral magnetic effect. 4,[12][13][14] The prospect of realizing an axion insulator has inspired much theoretical and experimental work. Only very recently, signatures of a dynamic axion field have been found on the surface of magnetically doped topological insulator thin films. [15][16][17] However, the axionic quasi-particle in these systems-the axionic polariton 3 -has so far eluded experimental detection. Alternatively, axion insulators have been predicted to arise in Weyl semimetals that are unstable towards the formation of a charge density wave (CDW). [18][19][20][21][22][23] In their parent state, Weyl semimetals are materials in which the low-energy electronic quasiparticles behave as chiral relativistic fermions without rest mass, known as Weyl fermions. [24][25][26][27] The Weyl fermions exist at isolated crossing points of conductance and valence bands-so called Weyl nodes-and their energy can be approximated with a linear dispersion relation ( Fig. 1 (a)). The Weyl nodes always occur in pairs of opposite "handedness" or chirality. At low energies and in the absence of interactions the chirality is a conserved quantum number, and the two chiral populations do not mix. Parallel electric and mag...

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mentioning

confidence: 99%

Axionic charge-density wave in the Weyl semimetal (TaSe4)2I

Gooth¹,

Bradlyn²,

Honnali³

et al. 2019

Nature

215

157

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“…Among them, the 5 d -transition-metal oxide is a promising class of materials, where the interplay between electron correlation and relativistic spin–orbit interaction yields the Dirac/Weyl semimetal coupled to the Mott physics or magnetism 9,10 . Indeed, the first prediction of magnetic Weyl semimetal has been done for the pyrochlore-type iridates, wherein signatures of correlated Weyl electron have been identified as anomalous magneto-transport phenomena 9–12 . However, the strong electron correlation usually decreases the electron mobility along the promotion of electron localization, and thus quantum transport of relativistic electron would be hardly observed in this class of materials.…”

Section: Introductionmentioning

confidence: 99%

Strong-correlation induced high-mobility electrons in Dirac semimetal of perovskite oxide

et al. 2019

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Electrons in conventional metals become less mobile under the influence of electron correlation. Contrary to this empirical knowledge, we report here that electrons with the highest mobility ever found in known bulk oxide semiconductors emerge in the strong-correlation regime of the Dirac semimetal of perovskite CaIrO3. The transport measurements reveal that the high mobility exceeding 60,000 cm2V−1s−1 originates from the proximity of the Fermi energy to the Dirac node (ΔE < 10 meV). The calculation based on the density functional theory and the dynamical mean field theory reveals that the energy difference becomes smaller as the system approaches the Mott transition, highlighting a crucial role of correlation effects cooperating with the spin-orbit coupling. The correlation-induced self-tuning of Dirac node enables the quantum limit at a modest magnetic field with a giant magnetoresistance, thus providing an ideal platform to study the novel phenomena of correlated Dirac electron.

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“…Moreover, recently relevant nanostructured pyrochlore materials have gained significant attention compared with their bulk counterparts in the areas of photoluminescence, [10][11][12][13] scintillation, [11][12][13] and magnetism. 14 In this context, La 2 Zr 2 O 7 and La 2 Hf 2 O 7 have been two standout pyrochlores for their suitability in various kinds of technological applications such as luminescence, scintillator, ferroelectric material, nuclear waste host, catalyst, and electrode material in fuel cells, etc. 9,[11][12][13][15][16][17][18][19][20] They are thermally stable, can accommodate dopant ions at both A and B sites, and have high radiation stability, etc.…”

Section: Introductionmentioning

confidence: 99%

On comparison of luminescence properties of La₂Zr₂O₇ and La₂Hf₂O₇ nanoparticles

et al. 2019

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Unveiling the underlying mechanisms of properties of functional materials, including the luminescence differences among similar pyrochlores A2B2O7, opens new gateways to select proper hosts for various optoelectronic applications by scientists and engineers. For example, although La2Zr2O7 (LZO) and La2Hf2O7 (LHO) pyrochlores have similar chemical compositional and crystallographic structural features, they demonstrate different luminescence properties both before and after doped with Eu3+ ions. Based on our earlier work, LHO‐based nanophosphors display higher photo‐ and radioluminescence intensity, higher quantum efficiency, and longer excited state lifetime compared to LZO‐based nanophosphors. Moreover, under electronic O2−→Zr4+/Hf4+ transition excitation at 306 nm, undoped LHO nanoparticles (NPs) have only violet blue emission, whereas LZO NPs show violet blue and red emissions. In this study, we have combined experimental and density functional theory (DFT) based theoretical calculation to explain the observed results. First, we calculated the density of state (DOS) based on DFT and studied the energetics of ionized oxygen vacancies in the band gaps of LZO and LHO theoretically, which explain their underlying luminescence difference. For Eu3+‐doped NPs, we performed emission intensity and lifetime calculations and found that the LHOE NPs have higher host to dopant energy transfer efficiency than the LZOE NPs (59.3% vs 24.6%), which accounts for the optical performance superiority of the former over the latter. Moreover, by corroborating our experimental data with the DFT calculations, we suggest that the Eu3+ doping states in LHO present at exact energy position (both in majority and minority spin components) where oxygen defect states are located unlike those in LZO. Lastly, both the NPs show negligible photobleaching highlighting their potential for bioimaging applications. This current report provides a deeper understanding of the advantages of LHO over LZO as an advanced host for phosphors, scintillators, and fluoroimmunoassays.

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Negative Longitudinal Magnetoresistance in the Density Wave Phase of Y2Ir2O7

Cited by 28 publications

References 42 publications

Axionic charge-density wave in the Weyl semimetal (TaSe4)2I

Axionic charge-density wave in the Weyl semimetal (TaSe4)2I

Strong-correlation induced high-mobility electrons in Dirac semimetal of perovskite oxide

On comparison of luminescence properties of La₂Zr₂O₇ and La₂Hf₂O₇ nanoparticles

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Negative Longitudinal Magnetoresistance in the Density Wave Phase of Y2Ir2O7

Cited by 28 publications

References 42 publications

Axionic charge-density wave in the Weyl semimetal (TaSe4)2I

Axionic charge-density wave in the Weyl semimetal (TaSe4)2I

Strong-correlation induced high-mobility electrons in Dirac semimetal of perovskite oxide

On comparison of luminescence properties of La2Zr2O7 and La2Hf2O7 nanoparticles

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Product

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On comparison of luminescence properties of La₂Zr₂O₇ and La₂Hf₂O₇ nanoparticles