Fe-Intercalation Dominated Ferromagnetism of van der Waals Fe3 GeTe2

Yueshen Wu; Yuxiong Hu; Cong Wang; Xiang Zhou; Xiaofei Hou; Wei Xia; Yiwen Zhang; Jinghui Wang; Yifan Ding; Jiadian He; Peng Dong; Song Bao; Jinsheng Wen; Yanfeng Guo; Kenji Watanabe; Takashi Taniguchi; Wei Ji; Zhu-Jun Wang; Jun Li

doi:10.1002/adma.202302568

Fe-Intercalation Dominated Ferromagnetism of van der Waals Fe₃ GeTe₂

Adv Mater. 2023 Sep;35(36):e2302568. doi: 10.1002/adma.202302568. Epub 2023 Jul 21.

Authors

Yueshen Wu¹, Yuxiong Hu¹, Cong Wang^{2

3}, Xiang Zhou^{1

4}, Xiaofei Hou^{1

4}, Wei Xia^{1

4}, Yiwen Zhang^{1

4}, Jinghui Wang^{1

4}, Yifan Ding^{1

4}, Jiadian He^{1

4}, Peng Dong^{1

4}, Song Bao⁵, Jinsheng Wen⁵, Yanfeng Guo^{1

4}, Kenji Watanabe⁶, Takashi Taniguchi⁷, Wei Ji², Zhu-Jun Wang¹, Jun Li^{1

8

9}

Affiliations

¹ School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
² Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872, China.
³ Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing, 100872, China.
⁴ ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 200031, China.
⁵ School of Physics & Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
⁶ Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
⁷ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
⁸ State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, China.
⁹ Wuhan National High Magnetic Field Center, Huazhong University of Science & Technology, Wuhan, 430074, China.

PMID: 37285053
DOI: 10.1002/adma.202302568

Abstract

Fe₃ GeTe₂ have proven to be of greatly intrigue. However, the underlying mechanism behind the varying Curie temperature (T_c ) values remains a puzzle. This study explores the atomic structure of Fe₃ GeTe₂ crystals exhibiting T_c values of 160, 210, and 230 K. The elemental mapping reveals a Fe-intercalation on the interstitial sites within the van der Waals gap of the high-T_c (210 and 230 K) samples, which are observed to have an exchange bias effect by electrical transport measurements, while Fe intercalation or the bias effect is absent in the low-T_c (160 K) samples. First-principles calculations further suggest that the Fe-intercalation layer may be responsible for the local antiferromagnetic coupling that gives rise to the exchange bias effect, and that the interlayer exchange paths greatly contribute to the enhancement of T_c . This discovery of the Fe-intercalation layer elucidates the mechanism behind the hidden antiferromagnetic ordering that underlies the enhancement of T_c in Fe₃ GeTe₂ .

Keywords: 2D materials; exchange bias; ferromagnetism.

Abstract

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