钾氨电子化合物中的准二维自旋-派尔斯相变  

Quasi-2D spin-Peierls transition through interstitial anionic electrons in K(NH_(3))_(2)

作　　者：丁驰 鲁清 郭照芃 黄天衡 王俊杰 韩瑜 邢定钰 孙建 Chi Ding;Qing Lu;Zhaopeng Guo;Tianheng Huang;Junjie Wang;Yu Han;Dingyu Xing;Jian Sun(National Laboratory of Solid State Microstructures,School of Physics and Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China)

机构地区：[1]National Laboratory of Solid State Microstructures,School of Physics and Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China

出　　处：《Science Bulletin》2024年第8期1027-1036,共10页科学通报（英文版）

基　　金：financial support from the National Key R&D Program of China(2022YFA1403201);the National Natural Science Foundation of China(12125404,11974162,and 11834006);the Fundamental Research Funds for the Central Universities。

摘　　要：Electron-phonon interactions and electron-electron correlations represent two crucial facets of condensed matter physics.For instance,in a half-filled spin-1/2 anti-ferromagnetic chain,the lattice dimerization induced by electron-nucleus interaction can be intensified by onsite Coulomb repulsion,resulting in a spin-Peierls state.Through first-principles calculations and crystal structure prediction methods,we have identified that under mild pressures,potassium and ammonia can form stable compounds:R3m K(NH_(3))_(2),Pm3 m K(NH_(3))_(2),and Cm K_(2)(NH_(3))_(3).Our predictions suggest that the R3 m K(NH_(3))_(2)exhibits electride characteristics,marked by the formation of interstitial anionic electrons(IAEs)in the interlayer space.These IAEs are arranged in quasi-two-dimensional triangular arrays.With increasing pressure,the electronic van-Hove singularity shifts toward the Fermi level,resulting in an augmented density of states and the onset of both Peierls and magnetic instabilities.Analyzing these instabilities,we determine that the ground state of the R3 m K(NH_(3))_(2)is the dimerized P2_(1)/m phase with zigzag-type anti-ferromagnetic IAEs.This state can be described by the triangular-lattice antiferromagnetic Heisenberg model with modulated magnetic interactions.Furthermore,we unveil the coexistence and positive interplay between magnetic and Peierls instability,constituting a scenario of spin-Peierls instability unprecedented in realistic 2D materials,particularly involving IAEs.This work provides valuable insights into the coupling of IAEs with the adjacent lattice and their spin correlations in quantum materials.

关 键 词：Quasi-two-dimensional Interstitial anionic electrons Potassium ammonia compounds Spin-Peierls transition ANTIFERROMAGNETISM 

分 类 号：O469[理学—凝聚态物理]