We present an infrared spectroscopy study of the magnetic topological insulator MnBi_(4)Te_7 with antiferromagnetic(AFM) order below the Neel temperature TN= 13 K. Our investigation reveals that the low-frequency opti...We present an infrared spectroscopy study of the magnetic topological insulator MnBi_(4)Te_7 with antiferromagnetic(AFM) order below the Neel temperature TN= 13 K. Our investigation reveals that the low-frequency optical conductivity consists of two Drude peaks, indicating a response of free carriers involving multiple bands. Interestingly, the narrow Drude peak grows strongly as the temperature decreases, while the broad Drude peak remains relatively unchanged. The onset of interband transitions starts around 2000 cm^(-1), followed by two prominent absorption peaks around 10000 cm^(-1) and 20000 cm^(-1). Upon cooling, there is a notable transfer of spectral weight from the interband transitions to the Drude response. Below TN, the AFM transition gives rise to small anomalies of the charge response due to a band reconstruction.These findings provide valuable insights into the interplay between magnetism and the electronic properties in MnBi_(4)Te_7.展开更多
Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared...Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.展开更多
The kagome system has attracted great interest in condensed matter physics due to its unique structure that canhost various exotic states such as superconductivity(SC),charge density waves(CDWs)and nontrivial topologi...The kagome system has attracted great interest in condensed matter physics due to its unique structure that canhost various exotic states such as superconductivity(SC),charge density waves(CDWs)and nontrivial topological states.The topological semimetal RbTi_(3)Bi_(5)consisting of a Ti kagome layer shares a similar crystal structure to the topologicalcorrelated materials AV_(3)Sb_(5)(A=K,Rb,Cs)but without the absence of CDW and SC.Systematic de Haas-van Alphenoscillation measurements are performed on single crystals of RbTi_(3)Bi_(5)to pursue nontrivial topological physics and exoticstates.Combining this with theoretical calculations,the detailed Fermi surface topology and band structure are investigated.A two-dimensional Fermi pocket b is revealed with a light effective mass,consistent with the semimetal predictions.TheLandau fan diagram of RbTi_(3)Bi_(5)reveals a zero Berry phase for the b oscillation in contrast to that of CsTi_(3)Bi_(5).Theseresults suggest that kagome RbTi_(3)Bi_(5)is a good candidate for exploring nontrivial topological exotic states and topologicalcorrelated physics.展开更多
Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties.Here we report the systematic magneto-transport studies on the Heusler alloy Nb_(x)Zr_(1-x)Co...Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties.Here we report the systematic magneto-transport studies on the Heusler alloy Nb_(x)Zr_(1-x)Co_(2)Sn considered as a ferromagnetic(FM)Weyl semimetal.The cusp anomaly of temperature-dependent resistivity and large isotropic negative magneto-resistivity(MR)emerge around the FM transition consistent with the theoretical half-metallic predictions.The prominent anomalous Hall effect(AHE)has the same behavior with the applied field along various crystal directions.The Nb doping introduces more disorder resulting in the enhancement of the upturn for the temperature-dependent resistivity in low temperatures.With Nb doping,the AHE exhibits systemic evolution with the Fermi level lifted.At the doping level of x=0.25,the AHE mainly originates from the intrinsic contribution related to non-trivial topological Weyl states.展开更多
基金Project supported by the the National Natural Science Foundation of China (Grant No.12274442)the National Key R&D Program of China (Grant No.2022YFA1403901)。
文摘We present an infrared spectroscopy study of the magnetic topological insulator MnBi_(4)Te_7 with antiferromagnetic(AFM) order below the Neel temperature TN= 13 K. Our investigation reveals that the low-frequency optical conductivity consists of two Drude peaks, indicating a response of free carriers involving multiple bands. Interestingly, the narrow Drude peak grows strongly as the temperature decreases, while the broad Drude peak remains relatively unchanged. The onset of interband transitions starts around 2000 cm^(-1), followed by two prominent absorption peaks around 10000 cm^(-1) and 20000 cm^(-1). Upon cooling, there is a notable transfer of spectral weight from the interband transitions to the Drude response. Below TN, the AFM transition gives rise to small anomalies of the charge response due to a band reconstruction.These findings provide valuable insights into the interplay between magnetism and the electronic properties in MnBi_(4)Te_7.
基金Project supported by the open research fund of Songshan Lake Materials Laboratory(Grant No.2021SLABFN11)the National Natural Science Foundation of China(Grant Nos.U2130101 and 92165204)+5 种基金Natural Science Foundation of Guangdong Province(Grant No.2022A1515010035)Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201011798)the Open Project of Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)the Open Project of Key Laboratory of Optoelectronic Materials and Technologies(Grant No.OEMT-2023-ZTS-01)the National Key R&D Program of China(Grant Nos.2023YFF0718400 and 2023YFA1406500)(national)college students innovation and entrepreneurship training program,Sun Yat-sen University(Grant No.202310359).
文摘Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFA1406500)the National Natural Science Foundation of China(Grant Nos.12174454,U2130101,and 92165204)+2 种基金the Guangdong Basic and Applied Basic Research Funds(Grant Nos.2024B1515020040 and 2022A1515010035)Guangzhou Basic and Applied Basic Research Funds(Grant No.2024A04J6417)Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008).
文摘The kagome system has attracted great interest in condensed matter physics due to its unique structure that canhost various exotic states such as superconductivity(SC),charge density waves(CDWs)and nontrivial topological states.The topological semimetal RbTi_(3)Bi_(5)consisting of a Ti kagome layer shares a similar crystal structure to the topologicalcorrelated materials AV_(3)Sb_(5)(A=K,Rb,Cs)but without the absence of CDW and SC.Systematic de Haas-van Alphenoscillation measurements are performed on single crystals of RbTi_(3)Bi_(5)to pursue nontrivial topological physics and exoticstates.Combining this with theoretical calculations,the detailed Fermi surface topology and band structure are investigated.A two-dimensional Fermi pocket b is revealed with a light effective mass,consistent with the semimetal predictions.TheLandau fan diagram of RbTi_(3)Bi_(5)reveals a zero Berry phase for the b oscillation in contrast to that of CsTi_(3)Bi_(5).Theseresults suggest that kagome RbTi_(3)Bi_(5)is a good candidate for exploring nontrivial topological exotic states and topologicalcorrelated physics.
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2023YFF0718400 and 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos.U2130101 and 92165204)+2 种基金the Natural Science Foundation of Guangdong Province,China (Grant No.2022A1515010035)the Open Project of Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices (Grant No.2022B1212010008)the Open Project of Key Laboratory of Optoelectronic Materials and Technologies (Grant No.OEMT-2023-ZTS-01)。
文摘Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties.Here we report the systematic magneto-transport studies on the Heusler alloy Nb_(x)Zr_(1-x)Co_(2)Sn considered as a ferromagnetic(FM)Weyl semimetal.The cusp anomaly of temperature-dependent resistivity and large isotropic negative magneto-resistivity(MR)emerge around the FM transition consistent with the theoretical half-metallic predictions.The prominent anomalous Hall effect(AHE)has the same behavior with the applied field along various crystal directions.The Nb doping introduces more disorder resulting in the enhancement of the upturn for the temperature-dependent resistivity in low temperatures.With Nb doping,the AHE exhibits systemic evolution with the Fermi level lifted.At the doping level of x=0.25,the AHE mainly originates from the intrinsic contribution related to non-trivial topological Weyl states.
