Wu Yueshen, Hu Yuxiong, Wang Cong, Zhou Xiang, Hou Xiaofei, Xia Wei, Zhang Yiwen, Wang Jinghui, Ding Yifan, He Jiadian, Dong Peng, Bao Song, Wen Jinsheng, Guo Yanfeng, Watanabe Kenji, Taniguchi Takashi, Ji Wei, Wang Zhu-Jun, Li Jun
School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing, 100872, China.
Adv Mater. 2023 Sep;35(36):e2302568. doi: 10.1002/adma.202302568. Epub 2023 Jul 21.
Fe GeTe have proven to be of greatly intrigue. However, the underlying mechanism behind the varying Curie temperature (T ) values remains a puzzle. This study explores the atomic structure of Fe GeTe crystals exhibiting T 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 (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 (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 . This discovery of the Fe-intercalation layer elucidates the mechanism behind the hidden antiferromagnetic ordering that underlies the enhancement of T in Fe GeTe .
铁锗碲已被证明极具吸引力。然而，居里温度（T）值变化背后的潜在机制仍是一个谜。本研究探索了居里温度值分别为160K、210K和230K的铁锗碲晶体的原子结构。元素映射显示，在高温（210K和230K）样品的范德华间隙内的间隙位置存在铁插入现象，通过电输运测量观察到这些样品具有交换偏置效应，而在低温（160K）样品中不存在铁插入或偏置效应。第一性原理计算进一步表明，铁插入层可能是产生交换偏置效应的局部反铁磁耦合的原因，并且层间交换路径对居里温度的升高有很大贡献。铁插入层的这一发现阐明了铁锗碲中居里温度升高背后隐藏的反铁磁有序的机制。
