Kagome lattice materials have attracted considerable attention due to their intriguing topological properties and potential applications in next-generation quantum and spintronic technologies. In particular, rare-earth permanent magnets with Kagome structure provide an ideal platform that combines robust magnetism with nontrivial quantum phenomena. However, their anomalous transport properties, particularly thermoelectric responses, remain insufficiently explored. In this work, we perform systematic first-principles calculations on the anomalous Hall and anomalous Nernst effects in Kagome permanent magnets RCo5 (R = Ce, La, Sm, Gd). We find that CeCo5 exhibits a pronounced anomalous Hall conductivity of about 1500 Omega^-1 cm^-1 while GdCo5 displays a substantial anomalous Nernst conductivity of 11 A m^-1 K^-1 within +/- 0.1 eV of the Fermi energy, both comparable to or surpassing the measured intrinsic values reported in many typical Weyl and Heusler magnets. These exceptional anomalous transport properties originate from Berry curvature hotspots near spin-orbit coupling induced band gaps. If validated, these theoretical predictions would be important for Berry-curvature-driven transport in magnetic intermetallics. Our results establish RCo5 compounds as versatile platforms for exploring Berry curvature-driven transport in tunable magnetic topological materials.
Analogous to the Hall effect, the Nernst effect is the generation of a transverse voltage due to a temperature gradient in the presence of a perpendicular magnetic field. The Nernst effect has promise for thermoelectric applications and as a probe of electronic structure. In magnetic materials, a so-called anomalous Nernst effect (ANE) is possible in zero magnetic field. Here we report a colossal ANE reaching 23 $μ$V/K in the ferromagnetic metal UCo$_{0.8}$Ru$_{0.2}$Al. Uranium's $5f$ electrons provide strong electronic correlations that lead to narrow bands, which are a known route to produci…
The discovery of magnetic topological semimetals recently attracted significant attention in the field of topology and thermoelectrics. In a thermoelectric device based on the Nernst geometry, an external magnet is required as an integral part. We report a zero-field Nernst effect in a newly discovered hard-ferromagnetic kagome-lattice Weyl-semimetal Co3Sn2S2. A maximum Nernst thermopower of 3 microvolt/K at 80 K in zero field is achieved in this magnetic Weyl-semimetal. Our results demonstrate the possibility of application of topological hard magnetic semimetals for low-power thermoelectric …
The topological kagome magnet (TKM) Fe3Sn2 exhibits unusual topological properties, flat electronic bands, and chiral spin textures, making it an exquisite materials platform to explore the interplay between topological band structure, strong electron correlations, and magnetism. Here we report the first synthesis of high-quality epitaxial (0001) Fe3Sn2 films with large intrinsic anomalous Hall effect close to that measured in bulk single crystals. In addition, we measured a large, anisotropic anomalous Nernst coefficient Syx of 1.26 μV/K, roughly 2-5x greater than that of common ferromagnets,…
Synthesis of crystallographically well-defined thin films of topological materials is important for unraveling their mesoscale quantum properties and for device applications. Mn$_3$Ge, an antiferromagnetic Weyl semimetal with a chiral magnetic structure on a Kagome lattice, is expected to have enhanced Berry curvature around Weyl nodes near the Fermi energy, leading to large anomalous Hall / Nernst effects and a large spin-Hall effect. Using magnetron sputtering, we have grown epitaxial thin films of hexagonal D0$_{19}$ Mn$_3$Ge that are flat and continuous. Large anomalous Nernst and inverse …
Kagome metal TbMn6Sn6 was recently discovered to be a ferrimagnetic topological Dirac material by scanning tunneling microscopy/spectroscopy measurements. Here, we report the observation of large anomalous Nernst effect and anomalous thermal Hall effect in this compound. The anomalous transverse transport is consistent with the Berry curvature contribution from the massive Dirac gaps in the 3D momentum space as demonstrated by our first-principles calculations. Furthermore, the transverse thermoelectric transport exhibits asymmetry with respect to the applied magnetic field, i.e., an exchange-…
Enhanced anomalous Nernst effect in Pr-doped kagome and honeycomb magnet LaCo$_5$
School of Physics, Zhejiang University（浙江大学物理学院）；School of Physics and Optical Engineering, Zhejiang University of Technology（浙江工业大学物理与光电工程学院）；State Key Laboratory of Silicon and Advanced Semiconductor Materials, Zhejiang University（浙江大学硅及先进半导体材料国家重点实验室）；Hefei National Laboratory（合肥国家实验室）；Wuhan National High Magnetic Field Center, Huazhong University of Science & Technology（华中科技大学武汉国家高磁场科学中心）
The kagome metal compounds $A$V$_3$Sb$_5$ ($A$ = K, Rb, and Cs) feature a wealth of phenomena including nontrivial band topology, charge density wave (CDW), and superconductivity. One intriguing property is the time-reversal symmetry breaking in the CDW state without local moments, which leads to anomalous transport responses. Here, we report the investigation of magneto-thermoelectric effects on high-quality CsV$_3$Sb$_5$ single crystals. A large anomalous Nernst effect is observed at temperatures below 30 K. Multiple Fermi surfaces with small effective masses are revealed by quantum oscillat…
Large longitudinal and anomalous transverse Magneto-thermoelectric effect in kagome antiferromagnet FeGe
Hangzhou Normal University（杭州师范大学）；Shanghai University（上海大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；Zhejiang University（浙江大学）；Chinese Academy of Sciences（中国科学院）；Northeastern University（东北大学）
During the past two decades, it has been established that a non-trivial electron wave-function topology generates an anomalous Hall effect (AHE), which shows itself as a Hall conductivity non-linear in magnetic field. Here, we report on an unprecedented case of field-linear AHE. In Mn$_3$Sn, a kagome magnet, the out-of-plane Hall response, which shows an abrupt jump, was discovered to be a case of AHE. We find now that the in-plane Hall response, which is perfectly linear in magnetic field, is set by the Berry curvature of the wavefunction. The amplitude of the Hall response and its concomitan…
Magnetic materials with kagome crystal structure exhibit rich physics such as frustrated magnetism, skyrmion formation, topological flat bands, and Dirac/Weyl points. Until recently, most studies on kagome magnets have been performed on bulk crystals or polycrystalline films. Here we report the synthesis of high-quality epitaxial films of topological kagome magnet Fe$_3$Sn$_2$ by atomic layer molecular beam epitaxy. Structural and magnetic characterization of Fe$_3$Sn$_2$ on epitaxial Pt(111) identifies highly ordered films with c-plane orientation and an in-plane magnetic easy axis. Studies o…
The anomalous Ettingshausen effect (AEE) in SmCo$_5$-type permanent magnets has been investigated in the high-temperature range from room temperature to around 600 K. The anomalous Ettingshausen coefficient of the SmCo$_5$ and (SmGd)Co$_5$ magnets monotonically increases with increasing the temperature and shows the similar temperature dependence, while the coefficient of SmCo$_5$ is slightly larger than that of (SmGd)Co$_5$ at high temperatures. The dimensionless figure of merit for AEE in SmCo$_5$ at high temperatures is much greater than the previous record obtained for the anomalous Nernst…
Magnetic materials with kagome crystal structure exhibit rich physics such as frustrated magnetism, skyrmion formation, topological flat bands, and Dirac/Weyl points. Until recently, most studies on kagome magnets have been performed on bulk crystals or polycrystalline films. Here we report the atomic layer molecular beam epitaxy synthesis of high-quality thin films of topological kagome magnet Fe${_3}$Sn${_2}$. Structural and magnetic characterization of Fe${_3}$Sn${_2}$ on epitaxial Pt(111) identifies highly ordered films with c-plane orientation and an in-plane magnetic easy axis. Studies o…
Magnetic States and Electronic Properties of Manganese-Based Intermetallic Compounds Mn$_2$YAl and Mn$_3$Z (Y = V, Cr, Fe, Co, Ni; Z = Al, Ge, Sn, Si, Pt)
