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Simultaneous Enhancement of Electron and Phonon Transport Properties via Magnetism Phase Transition in Fe x Co 2‐x TiGe Heusler Alloy
Author(s) -
Li Yongqiang,
Wang Hanwen,
Cui Wenjun,
Lin Weixiao,
Sun Yue,
Zhao Wen,
Sang Xiahan
Publication year - 2025
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.202500154
Subject(s) - condensed matter physics , materials science , seebeck coefficient , curie temperature , thermoelectric effect , magnetism , phonon scattering , ferromagnetism , thermoelectric materials , paramagnetism , scattering , phonon , thermal conductivity , thermodynamics , physics , optics , composite material
Abstract Magnetism offers an additional degree of freedom to control the electron and phonon transport properties of thermoelectric materials through various thermoelectromagnetic effects. To better understand the interplay among spin, carriers, and phonons, it is important to design material systems with intrinsic magnetic and thermoelectric properties. Here, it is demonstrated that Fe doping of the full Heusler alloy Co 2 TiGe simultaneously enhances its magnetic and thermoelectric performance. Aberration‐corrected scanning transmission electron microscopy (STEM) reveals that Fe atoms preferentially substitute for Co atoms within the Co 2 TiGe lattice, leading to increased saturation magnetization and a higher Curie temperature. This Fe substitution reduces the carrier concentration, enhancing the Seebeck coefficient and power factor, while also increasing magnetic scattering due to spin fluctuations during the ferromagnetic‐paramagnetic phase transition. Furthermore, the thermal conductivity is significantly reduced by enhanced phonon scattering from secondary phases and point defects. Consequently, a maximum ZT value of 0.066 is achieved at 600 K for Fe 0.4 Co 1.6 TiGe, representing a 663% increase compared to the undoped Co 2 TiGe.