Dynamical properties of site-diluted Heisenberg antiferromagnetic on the kagome bilayer

We present spin dynamical simulations of the site-diluted Heisenberg antiferromagnet with nearest neighbor interactions on a quasi-2D kagome bilayer. This geometrically frustrated lattice consists of two kagome layers connected by a triangular-lattice layer. We combine Monte Carlo method with precessional spin dynamics simulations to compute the dynamical structure factor of the classical spin liquid and study the thermal and dilution effects. The low frequency and long wavelength dynamics of the classical spin liquid in kagome bilayer is dominated by spin diffusion [1]. In the presence of spin vacancies, the dynamical properties of the diluted system can be understood within the two population picture [2,3]. The spin diffusion of the “correlated” spin clusters gives rise to an exponentially decaying autocorrelation function. On the other hand, the diffusive dynamics of the quasi-free “orphan” spins leads to a distinctive long time power-law tail in the autocorrelation function. We discuss the implications of our work for the glassy behaviors observed in the frustrated magnet SrCr_9pGa_12−9pO₁₉(SCGO).
[1] P. Saha, D. Zhang, S.-H. Lee, and G.-W. Chern, arXiv:1904.05863 (2019).
[2] C. L. Henley, Can. J. Phys. 79, 1307 (2001).
[3] P. Schiffer and I. Daruka, Phys. Rev. B 56, 13712 (1997).