报告题目：Novel physics and gate tunable spin-polarized energy band in ultrathin magnetic semiconductor CrPS4
报 告 人: 廖孟涵，北京量子信息科学研究院
报告时间：2025年4月23日10:00-11:30
报告地点：物理楼W361
内容摘要：The interplay between semiconducting physics and magnetism results in novel phenomena. In this talk, I will show that transistors fabricated with ultrathin CrPS4 layers -an A-type antiferromagnetic semiconductor- enable precise detection of novel magnetic properties and control over the spin of the electrons. In monolayer CrPS4, we observe a critical behavior throughout the ferromagnetic phase. This is illustrated by power-law magnetoconductance, with an exponent smaller than 1, in a phase diagram over 4 decades of magnetic field and 2 decades of temperature. The nonanalytical behavior is attributed to the presence of spin frustration induced by strain around defects. The power-law behaviors are consistent with the quantum Griffiths effect in 2D magnets. In bilayer CrPS4, in which the two ferromagnetic layers are antiferromagnetically coupled, we realize gate-switchable spin-polarized electrons by controlling the displacement field with double-gated transistors [1]. Accumulating electrons in the energy band of the top and bottom layer, which hosts opposite spin polarization, allows control of the magnetization of the electrons. Our work demonstrates that van der Waals 2D magnetic materials provide a great platform to investigate new physics.
[1] F. Yao#*, M. Liao#, M. Gibertini*, et al. “Switching the spin polarization of the conduction band in antiferromagnetic bilayer transistors on and off”, Nat. Nanotech, DOI: 10.1038/41565-025-01872-w
报告人简介：Menghan Liao is an associate research scientist in the Low-dimensional Quantum Materials Group at the Beijing Academy of Quantum Information Sciences. He obtained his B.S. degree from the School of the Gifted Young at the University of Science and Technology of China in 2015, and his Ph.D. degree from the Department of Physics at Tsinghua University in 2020. From 2021 to 2023, he worked as a postdoctoral fellow at the Department of Quantum Matter Physics at the University of Geneva. In 2024, he was awarded the Ambizione Project from the Swiss National Science Foundation and was promoted to a Scientific Collaborator (Research Associate). In 2025, he joined the Beijing Academy of Quantum Information Sciences. Menghan Liao is dedicated to the experimental study of novel quantum phenomena in low-dimensional materials, including (1) The mechanism of high-temperature superconductivity and other novel superconducting states; (2) Two-dimensional magnetic semiconductors; (3) Novel physical phenomena arising from topological band structures. Dr. Liao employs modern nano-fabrication techniques (such as van der Waals stacking and electron beam lithography) to prepare high-quality electrical devices and carries out electrical transport studies at low temperatures and high magnetic fields. Until February 2025, Menghan Liao has published 23 papers and has been cited over 2000 times, and his H-index is 13. 9 papers were published as the first author or co-first author, including 1 Nature Physics, 1 Nature Nanotechnology, 1 Physical Review X, 2 Nature Communications, 3 Nano Letters, and 1 Applied Physics Letters.
