arXiv subjects

Zixuan Jia

Publications and source records attributed to Zixuan Jia.

5 recordsLinked to original sources

arXiv2026

Interplay of magnetic and thermodynamic responses in the kagome-triangular system

Inspired by the recent experimental progress in pyrochlore derivative RE$_3$Sb$_3$A$_2$O$_{14}$ (A = Mg, Zn), we investigate the Hubbard model on the kagome lattice with an additional hopping $t'/t$, which enables continuous interpolation between the kagome and triangular lattices by using determinant quantum Monte Carlo simulations. We find that increasing $t'/t$ suppresses the nearest-neighbor antiferromagnetic correlations. Concurrently, the next-nearest-neighbor antiferromagnetic correlations are enhanced and closely associated with the emergence of a pronounced low-temperature peak in the specific heat. Increasing on-site interaction $U$ enhances magnetic correlations and shifts the associated $t'/t$ crossover points to larger values. We also discuss the sign problem to clarify which parameter region of our numerical simulations is accessible and reliable. Our results uncover the competition between frustration and correlations and the interplay of magnetic and thermodynamic responses in the kagome lattice, providing insights into correlated states in frustrated materials.

cond-mat.str-el↗

arXiv2026

Magnetic fluctuations near the Van Hove singularity in the kagome-lattice Hubbard model at finite doping

The kagome-lattice Hubbard model attracts widespread interest due to its flat-band and Van Hove singularity features, which can give rise to unconventional magnetism. We employ determinant quantum Monte Carlo simulations to systematically investigate the uniform magnetic susceptibility across a range of on-site interactions and electron fillings on a two-dimensional kagome lattice. Beyond the Van Hove singularity, dominant ferromagnetic fluctuations emerge. Magnetic susceptibility grows markedly with increasing interaction strength and decreasing temperature, indicating that the Van Hove singularity acts as a critical point for the crossover of dominant magnetic fluctuations. Finite-size analysis further suggests the potential stabilization of a finite-temperature ferromagnetic phase. We also examine the sign problem to identify numerically reliable parameter regimes. These results provide valuable insights into controlling magnetic fluctuations in kagome systems and establish a computational framework for exploring flat-band physics in regimes characterized by novel quantum phases and competing orders.

cond-mat.str-el↗

arXiv2025

Breathing-Driven Metal-Insulator Transition in Correlated Kagome Systems

Inspired by the recent discovery of breathing kagome materials $\rm Nb_3Cl_8$ and $\rm Nb_3TeCl_7$, we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice. Utilizing the determinant quantum Monte Carlo method, we first investigated the average sign problem in the breathing kagome lattice, which is significantly affected by both the breathing strength and the interaction strength. Secondly, we calculated the electronic kinetic energy, the direct current conductivity, and the electronic density of states at the Fermi level to determine the critical interaction strength for the metal-insulator transition. Our results indicate that the breathing effect, in conjunction with the interaction strength, drives the kagome system from a metal to an insulator. Finally, we evaluated the magnetic properties and constructed a phase diagram incorporating both transport and magnetic properties. The phase diagram reveals that as the interaction strength increases, the system transitions from a paramagnetic metal to a Mott insulator. Our research provides a theoretical guidance for utilizing the breathing effect to control the band gaps, conductivity, and magnetic properties of kagome materials with electronic interactions.

cond-mat.str-el↗

arXiv2024

Competition between $d$-wave and $d$+$is$-wave superconductivity in the Hubbard model on a checkerboard lattice

By employing determinant quantum Monte Carlo simulations, we investigate a checkerboard lattice with next-nearest-neighbor hopping $t'$ as the frustration-control parameter, which exhibits an energetically partial flat-band in the system. Our numerical simulation identifies the dominant pairing symmetry of the checkerboard lattice Hubbard model, and we reveal the competition between the $d$-wave and $d+is$ wave in the parameter space of electron filling $\avg{n}$ and frustration control parameter $t^{\prime}/t$. To ensure the reliability and accuracy of our results, we evaluate the sign problem. We also find that the spin susceptibility, the effective pairing interactions of different pairing symmetries and the superconducting instability are enhanced as the on-site Coulomb interaction increases, demonstrating that superconductivity is driven by strong electron--electron correlation. Our work provides a further understanding of pairing symmetry in the Hubbard model and improves prospects for exploring rich correlated behaviors in frustrated systems.

cond-mat.str-el↗

arXiv2023

Evolution of magnetic correlation in an inhomogeneous square lattice

We explore the magnetic properties of a two-dimensional Hubbard model on an inhomogeneous square lattice, which provides a platform for tuning the bandwidth of the flat band. In its limit, this inhomogeneous square lattice turns into a Lieb lattice, and it exhibits abundant properties due to the flat band structure at the Fermi level. By using the determinant quantum Monte Carlo simulation, we calculate the spin susceptibility, double occupancy, magnetization, spin structure factor, and effective pairing interaction of the system. It is found that the antiferromagnetic correlation is suppressed by the inhomogeneous strength and that the ferromagnetic correlation is enhanced. Both the antiferromagnetic correlation and ferromagnetic correlation are enhanced as the interaction increases. It is also found that the effective $d$-wave pairing interaction is suppressed by the increasing inhomogeneity. In addition, we also study the thermodynamic properties of the inhomogeneous square lattice, and the calculation of specific heat provide good support for our point. Our intensive numerical results provide a rich magnetic phase diagram over both the inhomogeneity and interaction.

cond-mat.str-el↗