Giant room temperature anomalous Hall effect and tunable topology in a ferromagnetic topological semimetal Co2MnAl

Li, Peigang; Koo, Jahyun; Ning, Wei; Li, Jinguo; Miao, Leixin; Min, Lujin; Zhu, Yanglin; Wang, Yu; Alem, Nasim; Liu, Chao Xing; Mao, Zhiqiang; Yan, Binghai

doi:10.1038/s41467-020-17174-9

Cited by 177 publications

(121 citation statements)

References 70 publications

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“…Although these values are smaller than that of the ordered Co 2 MnZ SC, they are comparable to those obtained in disordered Co 2 MnZ thin films. [33,44] xy | measured at 300 K for Fe 2 YZ, Co 2 MnGa [19,22,46] and Co 2 MnAl [32] SC, and Co 2 MnGa [43][44][45] and Co 2 Mn 1-x Si x [33] Figure 3c shows the calculated yx near room temperature. The anomalous component A yx of all four Fe 2 YZ SC reached values above 0.5 A m −1 K −1 , with a maximum value of 1.7 A m −1 K −1 , which is approaching the maximum value obtained in the representative magnetic Weyl systems Co 3 Sn 2 S 2 and Co 2 MnZ.…”

Section: Resultsmentioning

confidence: 99%

“…[ 3 ] To date, the investigations of Heusler compounds for anomalous transport have mainly focused on Co‐based members with a T c of approximately 694 K [ 30 ] for Co 2 MnGa [ 19 , 20 , 22 , 26 ] and Co 2 MnAl. [ 31 , 32 , 33 ] In contrast, low‐cost Fe‐based Heusler compounds with a much higher T c (up to 1000 K) [ 34 , 35 ] have rarely been studied for anomalous transverse transport. Very recently, Noky et al.…”

Section: Introductionmentioning

confidence: 99%

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Large Anomalous Hall and Nernst Effects in High Curie‐Temperature Iron‐Based Heusler Compounds

et al. 2021

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The interplay between topology and magnetism has recently sparked the frontier studies of magnetic topological materials that exhibit intriguing anomalous Hall and Nernst effects owning to the large intrinsic Berry curvature (BC). To better understand the anomalous quantum transport properties of these materials and their implications for future applications such as electronic and thermoelectric devices, it is crucial to discover more novel material platforms for performing anomalous transverse transport studies. Here, it is experimentally demonstrated that low-cost Fe-based Heusler compounds exhibit large anomalous Hall and Nernst effects. An anomalous Hall conductivity of 250-750 S cm −1 and Nernst thermopower of above 2 μV K −1 are observed near room temperature. The positive effect of anti-site disorder on the anomalous Hall transport is revealed. Considering the very high Curie temperature (nearly 1000 K), larger Nernst thermopowers at high temperatures are expected owing to the existing magnetic order and the intrinsic BC. This work provides a background for developing low-cost Fe-based Heusler compounds as a new material platform for anomalous transport studies and applications, in particular, near and above room temperature.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large Anomalous Hall and Nernst Effects in High Curie‐Temperature Iron‐Based Heusler Compounds

et al. 2021

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“…In the last decades, theoretical progress was made in identifying basic mechanisms, improving theoretical methods and revealing its deep relation to topology [12,13]. In recent years, there is an increasing interest in transport properties of systems with topological properties in material science [14][15][16], including Heusler compounds [17][18][19], Weyl semimetals [20][21][22], and graphene [23,24], and in other fields like in microcavities [25] and cold atoms [26].…”

Section: Introductionmentioning

confidence: 99%

“…The combination of both approaches, which is a systematic microscopic derivation combined with a Boltzmann-like physical interpretation, in order to find further relevant contributions is still subject of recent research [30]. The established connection between the intrinsic anomalous Hall conductivity and the Berry curvature [31][32][33][34][35] combined with ab initio band structure calculations [36,37] has become a powerful tool for combining theoretical and experimental results and is state-of-the-art in recent studies [14][15][16][17][18][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Longitudinal and anomalous Hall conductivity of a general two-band model

Mitscherling

2020

Phys. Rev. B

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We derive and analyze the longitudinal and the anomalous Hall conductivity for a general momentum-blockdiagonal two-band model. This model captures a broad spectrum of physically very different systems including Néel antiferromagnetic and spiral spin density waves as well as models that involve spin-orbit interaction and are known to show topological properties. We present a complete microscopic derivation for finite temperature and constant scattering rate that is diagonal and equal, but arbitrarily large for both bands. We identify two criteria that allow for a unique and physically motivated decomposition of the conductivities. On the one hand, we distinguish intraband and interband contributions that are defined by the involved quasiparticle spectral functions. On the other hand, we distinguish symmetric and antisymmetric contributions that are defined by the symmetry under the exchange of the current and the electric field directions. The (symmetric) intraband contributions generalize the formula of standard Boltzmann transport theory, which is valid only in the clean limit (small), whereas the interband contributions capture interband coherence effects beyond independent quasiparticles. We show that the symmetric interband contribution is a correction only present for finite and is controlled by the quantum metric. The antisymmetric interband contributions generalize the formula of the anomalous Hall conductivity in terms of the Berry curvature to finite. We study the clean (small) and dirty (large) limit analytically. The connection between the presented derivation and the Bastin and Streda formalism is given. We apply our results to a Chern insulator, a ferromagnetic multi-d-orbital, and a spiral spin density wave model.

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“…As a fundamental physical parameter, temperature plays an important role in many physical, chemical, and biological systems. Precise thermal sensing has thus become of great interest in many scientific, engineering, and industrial areas, such as novel materials [1][2][3] , energy harvesting 4,5 , biomedical studies and healthcare treatment [6][7][8][9][10][11] , and environmental monitoring [12][13][14] . For instance, precise and continuous monitoring of temperature changes in the human body is critical in understanding the thermal phenomenon of homeostasis and providing essential diagnostic information to identify appropriate treatment protocols for diseases such as COVID-19 15 , traumatic brain injury 16,17 , and cancer [18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

2021

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Temperature is one of the most fundamental physical properties to characterize various physical, chemical, and biological processes. Even a slight change in temperature could have an impact on the status or dynamics of a system. Thus, there is a great need for high-precision and large-dynamic-range temperature measurements. Conventional temperature sensors encounter difficulties in high-precision thermal sensing on the submicron scale. Recently, optical whispering-gallery mode (WGM) sensors have shown promise for many sensing applications, such as thermal sensing, magnetic detection, and biosensing. However, despite their superior sensitivity, the conventional sensing method for WGM resonators relies on tracking the changes in a single mode, which limits the dynamic range constrained by the laser source that has to be fine-tuned in a timely manner to follow the selected mode during the measurement. Moreover, we cannot derive the actual temperature from the spectrum directly but rather derive a relative temperature change. Here, we demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. The measurement relies on the patterns of multiple modes in the WGM spectrum instead of the changes of a particular mode. It can provide us with more information than the single-mode spectrum, such as the precise measurement of actual temperatures. Leveraging the high sensitivity of WGMs and eliminating the need to monitor particular modes, this work lays the foundation for developing a high-performance temperature sensor with not only superior sensitivity but also a broad dynamic range.

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Giant room temperature anomalous Hall effect and tunable topology in a ferromagnetic topological semimetal Co2MnAl

Cited by 177 publications

References 70 publications

Large Anomalous Hall and Nernst Effects in High Curie‐Temperature Iron‐Based Heusler Compounds

Large Anomalous Hall and Nernst Effects in High Curie‐Temperature Iron‐Based Heusler Compounds

Longitudinal and anomalous Hall conductivity of a general two-band model

Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

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