Giant anomalous Nernst effect and quantum-critical scaling in a ferromagnetic semimetal

Sakai, Akito; Mizuta, Yoshio; Nugroho, A. A.; Sihombing, Rombang Rizki; Koretsune, Takashi; Suzuki, Michi‐To; Takemori, Nayuta; Ishii, Ryuji; Nishio–Hamane, Daisuke; Arita, Ryotaro; Goswami, Pallab; Nakatsuji, Satoru

doi:10.1038/s41567-018-0225-6

Cited by 451 publications

(492 citation statements)

References 53 publications

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“…In AHE and ANE, the current is driven by an electric field and temperature gradient ∇ respectively, while a voltage is measured perpendicular to both the current and the magnetization M of the material. While the AHE is dominated by the sum of the Berry curvatures for all the occupied states, ANE is determined by the Berry curvature at the Fermi level F , thus providing a different probe of the Berry curvature near F and the topological nature of materials [16][17][18][19]. Therefore, FGT provides a unique platform for studying the ANE in 2D vdW ferromagnets and their topological properties.…”

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confidence: 99%

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe₃GeTe₂

2019

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Anomalous Nernst effect, a result of charge current driven by temperature gradient, provides a probe of the topological nature of materials due to its sensitivity to the Berry curvature near the Fermi level. Fe3GeTe2, one important member of the recently discovered two-dimensional van der Waals magnetic materials, offers a unique platform for anomalous Nernst effect because of its metallic and topological nature. Here, we report the observation of large anomalous Nernst effect in Fe3GeTe2. The anomalous Hall angle and anomalous Nernst angle are about 0.07 and 0.09 respectively, far larger than those in common ferromagnets. By utilizing the Mott relation, these large angles indicate a large Berry curvature near the Fermi level, consistent with the recent proposal for Fe3GeTe2 as a topological nodal line semimetal candidate. Our work provides evidence of Fe3GeTe2 as a topological ferromagnet, and demonstrates the feasibility of using twodimensional magnetic materials and their band topology for spin caloritronics applications.

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confidence: 99%

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe₃GeTe₂

2019

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“…extensively sought, leading to the recent revelation of magnetic topological insulator MnBi2Te4 [13][14][15][16][17][18][19][20]. Since 2016, researchers have also been searching for other types of topological materials with intrinsic magnetic order and uncovered a number of magnetic topological semimetals [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], which may lead to topologically-driven spintronics [37] and have become a focus center in the field . Extensive exploration of these materials has led to the discovery of exotic properties.…”

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confidence: 99%

Magnetization-governed magnetoresistance anisotropy in the topological semimetal CeBi

et al. 2019

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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 the 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, regardless of its large variation with the magnitude of the magnetic field and with temperature, is solely dictated by the field-induced magnetization that is orientated along a primary crystalline axis and flops under the influence of a rotating magnetic field. The results reveal the strong interaction between conduction electrons and magnetization in CeBi. They also indicate that magnetoresistance anisotropy can be used to uncover the magnetic behavior and the correlation between transport phenomena and magnetism in magnetic topological semimetals.Stimulated by the fascinating properties discovered in topological insulators [1], topological quantum materials have become an exciting frontier in condensed matter physics and materials science [2][3][4][5][6][7][8]. Among them, magnetic topological insulators with strong correlations between magnetism and nontrivial band topology exhibit exotic phenomena such as quantum anomalous Hall effect [5,[8][9][10][11] and axion insulator state [12]. However, those novel properties were observed in thin films of magnetic topological insulators converted from known topological insulators by doping magnetic atoms, e.g., chromium-doped (Bi,Sb)2Te3 [10,11] or in a ferromagnet-topological insulator-ferromagnet (FM-TI-FM) sandwich heterostructure [12]. Their fabrication requires advanced molecular beam epitaxy techniques [10][11][12]. The random magnetic dopants also inevitably introduce disorder that can hinder further exploration of topological quantum effects in the material [13,14]. Thus, topological insulators with intrinsic magnetic ordering have been

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“…These results can be generalized to any material hosting Weyl fermions by studying the corresponding changes in the band structure due to the optical lattice deformations. Similar analysis can be carried out in other magnetic Weyl semimetals, as Mn 3 Sn [43], Co 3 Sn 2 S 2 [44], or Co 2 MnGa [45].…”

Section: Discussionmentioning

confidence: 60%

Hall viscosity for optical phonons

2019

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We generalize the notion of dissipationless, topological Hall viscosity tensor to optical phonons in thin film Weyl semimetals. By using the strained Porphyrin thin film Weyl semimetal as a model example, we show how optical phonons can couple to Weyl electrons as chiral pseudo gauge fields. These chiral vector fields lead to a novel dissipationless two-rank viscosity tensor in the effective dynamics of optical phonons whose origin is the chiral anomaly. We also compute the contribution to this two rank Hall viscosity tensor due to the presence of an external magnetic field, whose origin is the conventional Hall response of Weyl electrons. Finally, the phonon dispersion relations of the system at the long-wavelength limit with and without an electromagnetic field are calculated showing a measurable shift in the Raman response of the system. Our results can be investigated by Raman scattering or infrared spectroscopy by attenuated total reflectance experiments.

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Giant anomalous Nernst effect and quantum-critical scaling in a ferromagnetic semimetal

Cited by 451 publications

References 53 publications

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe₃GeTe₂

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe₃GeTe₂

Magnetization-governed magnetoresistance anisotropy in the topological semimetal CeBi

Hall viscosity for optical phonons

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Giant anomalous Nernst effect and quantum-critical scaling in a ferromagnetic semimetal

Cited by 451 publications

References 53 publications

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe3GeTe2

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe3GeTe2

Magnetization-governed magnetoresistance anisotropy in the topological semimetal CeBi

Hall viscosity for optical phonons

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Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe₃GeTe₂

Large Anomalous Nernst Effect in a van der Waals Ferromagnet Fe₃GeTe₂