2024/04/25 by Yun-Tong Yang, Yang, Yun-Tong, Fuzhou Chen +3
Physics and Astronomy · #Computational Physics (physics.comp-ph) #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Quantum many-body systems #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con) #Theoretical and Computational Physics
paper · pdf · doi:10.48550/arxiv.2404.16330
openalex publication_date 2024/04/25 · openalex created_date 2024/04/27 · openalex updated_date 2026/07/28
Exploring the influence of frustration on the phases and related phase transitions in condensed matter physics is of fundamental importance in uncovering the role played by frustration. In the two-dimensional square lattice, a minimal frustration has been formulated in 1981 as the Shastry-Sutherland (SS) model described by competitions between the nearest-neighbor bond (J1) and the next-nearest-neighbor one (J2). In the two limits of α=J2/J1, i.e. α≪ 1 and α≫ 1, the corresponding phases are the Néel antiferromagnet (AFM) and the dimer-singlet(DS). Unfortunately, the intermediate regime remains controversial, and the nature of transition from the Néel AFM to the intermediate state is also unclear. Here we provide a pattern language to explore the SS model and take the lattice size L=4 ×4 with periodic boundary condition. We firstly diagonalize the Hamiltonian in an operator space to obtain all fundamental spin-patterns and then analyze their energy and occupancy evolutions with the frustration parameter κ=α/ (1+α). Our results indicate that the intermediate regime is characterized by diagonal two-domain spin-pattern while the Néel AFM state has a diagonal single-domain and the DS has mixings of diagonal single- and four-domain. While the transition from the DS to the intermediate phase occurred around αc = 1.5 is the first-order in nature, consistent with that in literature, the one from the intermediate phase to the AFM is clearly seen around αc = 1.277, where it has a reversal of the contributions from the single- and two-domain patterns to the ground state. The result indicates that the pattern language is powerful in identifying the possible phases in frustrated models.