48th Vietnam Conference on Theoretical Physics (VCTP48)
Hội nghị Vật lý lý thuyết Việt Nam lần thứ 48
Đà Nẵng, 31 July  3 August, 2023

ProgrammeP.35  Poster, VCTP48 Date: Tuesday, 1 August 2023 Time: 08:30  10:00 Quasiresonant diffusion of wave packets in onedimensional disordered mosaic latticesBa Phi Nguyen (1), Duy Khuong Phung (2) and Kihong Kim (3) (1) Department of Basic Sciences, Mientrung University of Civil Engineering, Vietnam and Research Institute for Basic Sciences, Ajou University, Korea; (2) Computing Fundamentals Department, FPT University, Vietnam; (3) Department of Physics, Ajou University, Korea and School of Physics, Korea Institute for Advanced Study, Korea We investigate numerically the time evolution of wave packets incident on onedimensional semiinfinite lattices with mosaic modulated random onsite potentials, which are characterized by the integervalued modulation period $\kappa$ and the disorder strength $W$ [1]. For Gaussian wave packets with the central energy $E_{0}$ and a small spectral width, we perform extensive numerical calculations of the disorderaveraged timedependent reflectance, $\langle R(t) \rangle$, for various values of $E_{0}$, $\kappa$, and $W$. We find that the longtime behavior of $\langle R(t) \rangle$ obeys a power law of the form $t^{\gamma}$ in all cases. In the presence of the mosaic modulation, $\gamma$ is equal to $2$ for almost all values of $E_{0}$, implying the onset of the Anderson localization, while at a finite number of discrete values of $E_{0}$ dependent on $\kappa$, $\gamma$ approaches $3/2$, implying the onset of the classical diffusion. This phenomenon is independent of the disorder strength and arises in a quasiresonant manner such that $\gamma$ varies rapidly from $3/2$ to $2$ in a narrow energy range as $E_{0}$ varies away from the quasiresonance values. We deduce a simple analytical formula for the quasiresonance energies and provide an explanation of the delocalization phenomenon based on the interplay between randomness and band structure and the node structure of the wave functions. We explore the nature of the states at the quasiresonance energies using a finitesize scaling analysis of the average participation ratio and find that the states are neither extended nor exponentially localized, but critical states. References: [1]. B. P. Nguyen, D. K. Phung and K. Kim, Phys. Rev. B 106, 134204 (2022). Presenter: Nguyen Ba Phi 
Institute of Physics, VAST

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