1、聚焦低维功能氧化物、铁电与反铁电薄膜体系的原子级可控制备与结构调控。重点开展硅基大面积外延薄膜生长研究，围绕畴壁、晶界、界面及缺陷等微观结构单元，开展多尺度结构设计与精准调控，为解析电介质材料本征物理机制、实现低功耗性能优化奠定材料基础。 

2、主攻电介质体系耗散本征机制、多场物性及功能效应基础研究。围绕铁电、介电、多铁材料体系，系统探究磁电耦合、界面自旋输运、电光响应、微波介电可调等物理特性；厘清多尺度结构耦合引发的耗散机理，建立电介质材料低功耗普适性调控理论，破解功能器件能效提升的核心瓶颈。 

3、面向新一代信息技术开展低功耗功能器件与应用技术探索。立足铁电、反铁电及氧化物电介质的独特物性，面向 5G/6G 通信、高速光互连、信息存储、微纳传感等应用场景，研发低耗散电光、微波介电、储能及集成电子功能器件，推动基础物理研究向工程化应用落地。

Selected Publications：

[17] Yu Yun†, Liyan Wu†*, Drew Behrendt†, Hao Pan†, Menglin Zhu, Michael Xu, Anthony J. Ruffino, John Carroll, Irina Baraban, Zishen Tian, Xianfei Xu, Dongfang Chen, Brendan M. Hanrahan, Lane W. Martin, James M. LeBeau, Andrew M. Rappe, Ilya Grinberg and Jonathan E. Spanier*, “Intrinsic relaxor in rocksalt cation-ordered material induced by (anti)ferroelectric phase competition” Nature Communications (2026) (in press)

[16] Xin Li†, Yu Yun†*, Guodong Ren, Arashdeep Singh Thind, Amit Kumar Shah, Rohan Mishra, and Xiaoshan Xu*, “Removing the Critical Thickness of Improper Ferroelectrics via Interfacial Reconstruction” Nano Letters 25, 12509 (2025).

[15] Yu Yun, Liyan Wu, Drew Behrendt, Pariasadat Musavigharavi, Dhiren K. Pradhan, Yunfei He, Yichen Guo, Rajeev Kumar Rai, Songsong Zhou, Craig L. Johnson, Eric Stach, Joshua C. Agar, Brendan M. Hanrahan, Deep Jariwala, Roy H. Olsson, Andrew M. Rappe, Jonathan E. Spanier*, “2D, Physical-Vapor Growth of Low-Coercivity, Epitaxial Ferroelectric Sc_0.3Al_0.7N on Scalable Substrates” Advanced Materials 37, 2501931 (2025).

[14] Aiji Wang, Rui Chen, Yu Yun*, Jeff Xu*, and Jinxing Zhang*, “Review of Ferroelectric Materials and Devices Towards Ultralow Voltage Operation” Advanced Functional Materials 35, 2412332 (2025) (Review).

[13] Xin Li†, Yu Yun†*, and Xiaoshan Xu*, “Recent Progress on Multiferroic Hexagonal Rare-Earth Ferrites (h-RFeO₃, R = Y, Dy-Lu)” Journal of Physics D: Applied Physics 58, 073003 (2025) (Review).

[12] Xin Li†, Yu Yun†*, Pratyush Buragohain, Haidong Lu, Arashdeep Singh Thind, Donald A.Walko, Detian Yang, Rohan Mishra, Alexei Gruverman, and Xiaoshan Xu*, “Dual mechanisms for transient capacitance anomaly in improper ferroelectrics” Physical Review Letters 133, 256801 (2024).

[11] Xin Li†, Yu Yun†*, Arashdeep Singh Thind, Yuewei Yin, Qiang Li, Wenbin Wang, Alpha T. N’Diaye, Corbyn Mellinger, Xuanyuan Jiang, Rohan Mishra, and Xiaoshan Xu*, “Domain-wall magnetoelectric coupling in multiferroic hexagonal YbFeO₃ films” Scientific Reports 13, 1755 (2023).

[10] Yu Yun†, Pratyush Buragohain†, Ming Li†, Zahra Ahmadi, Yizhi Zhang, Xin Li, Haohan Wang, Jing Li, Ping Lu, Lingling Tao, Haiyan Wang, Jeffrey E. Shield, Evgeny Y. Tsymbal*, Alexei Gruverman*, and Xiaoshan Xu*, “Intrinsic ferroelectricity in Y-doped HfO₂ thin films” Nature Materials 21, 903 (2022).

[9] Yu Yun†, Pratyush Buragohain†, Arashdeep Singh Thind, Yuewei Yin, Xin Li, Xuanyuan Jiang, Rohan Mishra, Alexei Gruverman, and Xiaoshan Xu*, “Spontaneous polarization in ultrathin improper ferroelectric/dielectric bilayer in a capacitor structure at cryogenic temperatures”, Physical Review Applied 18, 034071 (2022).

[8] Detian Yang†, Yu Yun†*, Arjun Subedi, Nicholas E. Rogers, David M. Cornelison, Peter A. Dowben, and Xiaoshan Xu*, “Colossal intrinsic exchange bias in epitaxial CoFe₂O₄/Al₂O₃ thin films”, Physical Review B 103, 224405 (2021).

[7] Yang Ma†, Yu Yun†, Yuehui Li, Wenyu Xing, Yunyan Yao, Ranran Cai, Yangyang Chen, Yuan Ji, Peng Gao, Xin-Cheng Xie, and Wei Han*, “Interface ferromagnetism and anomalous Hall effect of CdO/ferromagnetic-insulator heterostructures”, Physics Review Materials 3, 054410 (2019).

[6] Yu Yun†, Yang Ma†, Tang Su, Wenyu Xing, Yangyang Chen, Yunyan Yao, Ranran Cai, Wei Yuan, and Wei Han*, “Role of La doping for Topological Hall Effect in Epitaxial EuO Films”, Physical Review Materials 2, 034201 (2018).

[5] Hongrui Zhang†, Yu Yun†, Xuejing Zhang†, Hui Zhang, Yang Ma, Xi Yan, Fei Wang, Gang Li, Rui Li, Tahira Khan, Yuansha Chen, Wei Liu, Fengxia Hu, Banggui Liu, Baogen Shen, Wei Han, and Jirong Sun*, “High-Mobility Spin-Polarized Two-Dimensional Electron Gases at EuO/KTaO₃ Interfaces”, Physical Review Letters 121, 116803 (2018).

[4] Yu Yun†, Yang Ma†, Songsheng Tao, Wenyu Xing, Yangyang Chen, Tang Su, Wei Yuan, Jian Wei, Xi Lin, Qian Niu, X. C. Xie, and Wei Han*, “Observation of long phase-coherence length in epitaxial La-doped CdO thin films”, Physical Review B 96, 245310 (2017).

[3] Yu Yun, Haoliang Huang, Dechao Meng, Zhangzhang Cui, Jianlin Wang, Zhengping Fu, Ranran Peng, Xiaofang Zhai, and Yalin Lu*, “Reduced growth temperature of Bi₆FeCoTi₃O₁₈ thin films by conductive bottom layers”, Journal of Crystal Growth 454, 25 (2016).

[2] Yu Yun, Chao Ma, Xiaofang Zhai, Haoliang Huang, Dechao Meng, Jianlin Wang, Zhengping Fu, Ranran Peng, Brown, Gail J., and Yalin Lu*, “Interface Engineering in Epitaxial Growth of Layered Oxides via a Conducting Layer Insertion”, Applied Physics Letters 107, 011602 (2015).

[1] Yu Yun, Xiaofang Zhai, Chao Ma, Haoliang Huang, Dechao Meng, Zhangzhang Cui, Jianlin Wang, Zhengping Fu, Ranran Peng, Gail J. Brown, and Yalin Lu*, “Growth of single crystalline Bi₆FeCoTi₃O₁₈ thin films and their magnetic-ferroelectric properties”, Applied Physics Express 8, 054001 (2015).