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1. ErMn ₆ Sn ₆ : A Promising Kagome Antiferromagnetic Candidate for Room‐Temperature Nernst Effect‐Based Thermoelectrics

   https://doi.org/10.1002/adfm.202418715  

   Emmanuel, Olajumoke Oluwatobiloba; Gupta, Shuvankar; Ke, Xianglin (September 2025, Advanced Functional Materials)

   Abstract The Nernst effect, the generation of a tranverse electric voltage in the presence of longitudinal thermal gradient, has garnered significant attention in the realm of magnetic topological materials due to its superior potential for thermoelectric applications. In this work, the electronic and thermoelectric transport properties of a Kagome magnet ErMn₆Sn₆are investigated, a compound showing an incommensurate antiferromagnetic phase followed by a ferrimagnetic phase transition upon cooling. It is shown that in the antiferromagnetic phase ErMn₆Sn₆exhibits both topological Nernst effect and anomalous Nernst effect, analogous to the electric Hall effects, with the Nernst coefficient reaching 1.71 µV K⁻¹ at 300 K and 3 T. This value surpasses that of most of previously reported state‐of‐the‐art canted antiferromagnetic materials and is comparable to recently reported other members of RMn₆Sn₆(R = rare‐earth, Y, Lu, Sc) compounds, which makes ErMn₆Sn₆a promising candidate for advancing the development of Nernst effect‐based thermoelectric devices. 

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2. Large Anomalous and Topological Hall Effect and Nernst Effect in a Dirac Kagome Magnet Fe ₃ Ge

   https://doi.org/10.1002/adfm.202511059  

   Xu, Chunqiang; Gupta, Shuvankar; Tan, Hengxin; Bae, Hyeonhu; Emmanuel, Olajumoke Oluwatobiloba; Xu, Mingyu; Wu, Yan; Xu, Xiaofeng; Zhang, Pengpeng; Xie, Weiwei; et al (October 2025, Advanced Functional Materials)

   Abstract Searching for Kagome magnets with novel magnetic and electronic properties has been attracting significant efforts recently. Here, the magnetic, electronic, and thermoelectric properties of Fe₃Ge single crystals with Fe atoms forming a slightly distorted Kagome lattice are reported. It is shown that Fe₃Ge exhibits a large anomalous Hall effect and anomalous Nernst effect. The observed anomalous transverse thermoelectric conductivity reaches ≈4.6 A m⁻¹ K⁻¹, which is larger than the conventional ferromagnets and most of the topological ferromagnets reported in literature. The first‐principles calculations suggest that these exceptional transport properties are dominated by the intrinsic mechanism, which highlights the significant contribution of the Berry curvature of massive Dirac gaps in the momentum space. Additionally, a topological Hall resistivity of 0.9 µΩ cm and a topological Nernst coefficient of 1.2 µV K⁻¹are also observed, which are presumably ascribed to the Berry phase associated with the field‐induced non‐zero scalar spin chirality. These features highlight the synergic effects of the Berry phases in both momentum space and real space of Fe₃Ge, which render it an excellent candidate for room‐temperature thermoelectric applications based on transverse transport. 

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3. Magnetism and Thermoelectric Properties of the Zintl Semiconductor: Eu ₂₁ Zn ₄ As ₁₈

   https://doi.org/10.1021/acs.chemmater.4c02200  

   Islam, Md Minhajul; Wróblewska, Maria; Shen, Zihao; Toberer, Eric S; Taufour, Valentin; Kauzlarich, Susan M (December 2024, Chemistry of Materials)

   Compositional diversity and intriguing structural features have made Zintl phases excellent candidates as thermoelectric materials. Zintl phase with 21-4-18 composition has shown high thermoelectric performance in the mid- to high-temperature ranges. The complex crystal structure and favorable transport properties of these compounds indicate the potential for high thermoelectric efficiency. Arsenic-based Eu21Zn4As18, belonging to the Ca21Mn4Sb18 structure type, exhibits a semiconductor-like p-type transport behavior and has a calculated band gap of 0.49 eV. The compound is paramagnetic at high temperatures, with an antiferromagnetic transition occurring at T-N = similar to 10 K. The moment obtained from the Curie-Weiss data fit aligns with Eu2+ ions. At the same time, the field-dependent measurement at 2 K indicates complex magnetic ordering with a saturation moment consistent with Eu2+ ions. Pristine Eu21Zn4As18 exhibits an ultralow lattice thermal conductivity of 0.40 W m(-1) K-1 at 873 K. Electronic transport properties measurement shows evidence of bipolar conduction across much of the measured temperature range (450-780 K). However, the Seebeck coefficient remains extremely high (>440 mu V K-1) across this range, indicating the potential for high zT if an appropriate dopant is found. This work represents the first report on the temperature-dependent thermal conductivity, Seebeck coefficient, and thermoelectric efficiency of the arsenic-containing Zintl phase with 21-4-18 composition, showcasing its promise for further optimization of the thermoelectric performance. 

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4. Extraordinary Thermoelectric Properties of Topological Surface States in Quantum‐Confined Cd ₃ As ₂ Thin Films

   https://doi.org/10.1002/adma.202311644  

   Ouyang, Wenkai; Lygo, Alexander C; Chen, Yubi; Zheng, Huiyuan; Vu, Dung; Wooten, Brandi L; Liang, Xichen; Heremans, Joseph P; Stemmer, Susanne; Liao, Bolin (July 2024, Advanced Materials)

   Abstract Topological insulators and semimetals have been shown to possess intriguing thermoelectric properties promising for energy harvesting and cooling applications. However, thermoelectric transport associated with the Fermi arc topological surface states on topological Dirac semimetals remains less explored. This work systematically examines thermoelectric transport in a series of topological Dirac semimetal Cd₃As₂thin films grown by molecular beam epitaxy. Surprisingly, significantly enhanced Seebeck effect and anomalous Nernst effect are found at cryogenic temperatures when the Cd₃As₂layer is thin. In particular, a peak Seebeck coefficient of nearly 500 µV K⁻¹and a corresponding thermoelectric power factor over 30 mW K⁻² m⁻¹are observed at 5 K in a 25‐nm‐thick sample. Combining angle‐dependent quantum oscillation analysis, magnetothermoelectric measurement, transport modeling, and first‐principles simulation, the contributions from bulk and surface conducting channels are isolated and the unusual thermoelectric properties are attributed to the topological surface states. The analysis showcases the rich thermoelectric transport physics in quantum‐confined topological Dirac semimetal thin films and suggests new routes to achieving high thermoelectric performance at cryogenic temperatures. 

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5. Measured and simulated thermoelectric properties of FeAs _2−x Se _x ( x = 0.30–1.0): from marcasite to arsenopyrite structure

   https://doi.org/10.1039/d0ma00371a  

   Perez, Christopher J.; Devlin, Kasey P.; Skaggs, Callista M.; Tan, Xiaoyan; Frank, Corey E.; Badger, Jackson R.; Kang, Chang-Jong; Emge, Thomas J.; Kauzlarich, Susan M.; Taufour, Valentin; et al (August 2020, Materials Advances)

   null (Ed.)

   FeAs 2−x Se x ( x = 0.30–1.0) samples were synthesized as phase pure powders by conventional solid-state techniques and as single crystals ( x = 0.50) from chemical vapor transport. The composition of the crystals was determined to be Fe 1.025(3) As 1.55(3) Se 0.42(3) , crystallizing in the marcasite structure type, Pnnm space group. FeAs 2−x Se x (0 < x < 1) was found to undergo a marcasite-to-arsenopyrite ( P 2 1 / c space group) structural phase transition at x ∼ 0.65. The structures are similar, with the marcasite structure best described as a solid solution of As/Se, whereas the arsenopyrite has ordered anion sites. Magnetic susceptibility and thermoelectric property measurements from 300–2 K were performed on single crystals, FeAs 1.50 Se 0.50 . Paramagnetic behavior is observed from 300 to 17 K and a Seebeck coefficient of −33 μV K −1 , an electrical resistivity of 4.07 mΩ cm, and a very low κ l of 0.22 W m −1 K −1 at 300 K are observed. In order to determine the impact of the structural transition on the high-temperature thermoelectric properties, polycrystalline FeAs 2−x Se x ( x = 0.30, 0.75, 0.85, 1.0) samples were consolidated into dense pellets for measurements of thermoelectric properties. The x = 0.85 sample shows the best thermoelectric performance. The electronic structure of FeAsSe was calculated with DFT and transport properties were approximately modeled above 500 K. 

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