Large Anomalous Nernst Effects at Room Temperature in Fe3 Pt Thin Films

Minghang Li; Hanqi Pi; Yunchi Zhao; Ting Lin; Qinghua Zhang; Xinzhe Hu; Changmin Xiong; Zhiyong Qiu; Lichen Wang; Ying Zhang; Jianwang Cai; Wuming Liu; Jirong Sun; Fengxia Hu; Lin Gu; Hongming Weng; Quansheng Wu; Shouguo Wang; Yunzhong Chen; Baogen Shen

doi:10.1002/adma.202301339

Large Anomalous Nernst Effects at Room Temperature in Fe₃ Pt Thin Films

Adv Mater. 2023 Aug;35(32):e2301339. doi: 10.1002/adma.202301339. Epub 2023 Jul 1.

Authors

Minghang Li^{1

2}, Hanqi Pi^{1

2}, Yunchi Zhao¹, Ting Lin^{1

2}, Qinghua Zhang¹, Xinzhe Hu¹, Changmin Xiong³, Zhiyong Qiu⁴, Lichen Wang⁵, Ying Zhang^{1

2}, Jianwang Cai^{1

2}, Wuming Liu^{1

2}, Jirong Sun^{1

2}, Fengxia Hu^{1

2}, Lin Gu¹, Hongming Weng^{1

2}, Quansheng Wu^{1

2}, Shouguo Wang⁶, Yunzhong Chen^{1

2}, Baogen Shen^{1

2

5

7}

Affiliations

¹ Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
² School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
³ Department of Physics, Beijing Normal University, Beijing, 100875, China.
⁴ School of Material Science and Engineering, Dalian University of Technology, Dalian, 116024, China.
⁵ Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.
⁶ School of Materials Science and Engineering, Anhui University, Hefei, 230601, China.
⁷ Ganjiang Innovation Academy, Chinese Academy of Sciences, Ganzhou, 341000, China.

PMID: 37308132
DOI: 10.1002/adma.202301339

Abstract

Heat current in ferromagnets can generate a transverse electric voltage perpendicular to magnetization, known as anomalous Nernst effect (ANE). ANE originates intrinsically from the combination of large Berry curvature and density of states near the Fermi energy. It shows technical advantages over the conventional longitudinal Seebeck effect in converting waste heat to electricity due to its unique transverse geometry. However, materials showing giant ANE remain to be explored. Herein, a large ANE thermopower of S_yx ≈ 2 µV K^-1 at room temperature in ferromagnetic Fe₃ Pt epitaxial films is reported, which also show a giant transverse thermoelectric conductivity of α_yx ≈ 4 A K^-1 m^-1 and a remarkable coercive field of 1300 Oe. The theoretical analysis reveals that the strong spin-orbit interaction in addition to the hybridization between Pt 5d and Fe 3d electrons leads to a series of distinct energy gaps and large Berry curvature in the Brillouin zone, which is the key for the large ANE. These results highlight the important roles of both Berry curvature and spin-orbit coupling in achieving large ANE at zero magnetic field, providing pathways to explore materials with giant transverse thermoelectric effect without an external magnetic field.

Keywords: Berry curvature; anomalous Nernst effect; ferromagnetism; spin-orbit interactions; transverse thermoelectric effect.

Abstract

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