Abstract
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(NH3)2,Pm3m K(NH3)2,and Cm K2(NH3)3.Our predictions suggest that the R3 m K(NH3)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(NH3)2 is the dimerized P2i/m phase with zigzag-type anti-ferromagnetic IAEs.This state can be described by the triangular-lattice antiferromag-netic 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.
基金项目
National Key R&D Program of China(2022YFA1403201)
National Natural Science Foundation of China(12125404)
National Natural Science Foundation of China(11974162)
National Natural Science Foundation of China(11834006)
Fundamental Research Funds for the Central Universities()
High-Performance Computing Center of Collaborative Innovation Center of Advanced Microstructures,the highperformance superco()
NETL
NSTL
万方数据