Large Magneto‐Transverse and Longitudinal Thermoelectric Effects in the Magnetic Weyl Semimetal TbPtBi

• Published in: Advanced materials (Weinheim) 2023-01, Vol.35 (2), p.e2206941-n/a
• Main Authors: Wang, Honghui, Zhou, Zizhen, Ying, Jianjun, Xiang, Ziji, Wang, Rui, Wang, Aifeng, Chai, Yisheng, He, Mingquan, Lu, Xu, Han, Guang, Pan, Yu, Wang, Guoyu, Zhou, Xiaoyuan, Chen, Xianhui
• Format: Article
• Language: English
• Subjects: Berry curvature; bipolar effect; chiral anomaly; Current carriers; Magnetoresistance; Magnetoresistivity; magneto‐thermoelectric; Materials science; Metalloids; Power factor; topological semimetals; Topology
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202206941

Magnetic topological semimetals provide new opportunities for power generation and solid‐state cooling based on thermoelectric (TE) effect. The interplay between magnetism and nontrivial band topology prompts the magnetic topological semimetals to yield strong transverse TE effect, while the longitudinal TE performance is usually poor. Herein, it is demonstrated that the magnetic Weyl semimetal TbPtBi has high value for both transverse and longitudinal thermopower with large power factor (PF). At 300 K and 13.5 Tesla, the transverse thermopower and PF reach up to 214 µV K−1 and 35 µW cm−1 K−2, respectively, which are comparable to those of state‐of‐the‐art TE materials. Combining first‐principles calculations, longitudinal magnetoresistance and planar Hall resistance measurements, and two‐band model fitting, the large transverse thermopower and PF are attributed to both bipolar effect and large Hall angle. Moreover, the imperfectly compensated charge carriers and large transverse magnetoresistance induce the maximum magneto‐longitudinal thermopower of 251 µV K−1 with a PF of 24 µW cm−1 K−2 at 150 K and 13.5 Tesla, which is two times higher than that at zero magnetic field. This work demonstrates the great potential of topological semimetals for TEs and offers a new excellent candidate for magneto‐TEs. Huge magneto‐transverse and longitudinal power factors are simultaneously detected in the magnetic Weyl semimetal TbPtBi. This can be ascribed to the magnetic field‐enhanced transverse and longitudinal thermopower induced by bipolar effect, and large Hall angle related to the large net Berry curvature and high carrier mobility, and the incompletely compensated charge carriers and large transverse magnetoresistance, respectively.