arXiv subjects

Che-Hao Chang

Publications and source records attributed to Che-Hao Chang.

2 recordsLinked to original sources

arXiv2024

Two-dimensional Keldysh theory for non-resonant strong-field ionization of monolayer 2D materials

The Keldysh theory of photoionization for solids is generalized to atomically thin two-dimensional semiconductors. We derive a closed-form formula and its asymptotic forms for a two-band model with a Kane dispersion. These formulas exhibit characteristically different behaviors from their bulk counterparts which are attributed to the scaling of the 2D density of states. We validate our formulas by comparing them to recent strong-field ionization experiments in monolayer MoS2 with good agreement. Our work is expected to find a wide range of applications in intense light - 2D material interaction.

physics.optics↗

arXiv2021

Frequency-induced Negative Magnetic Susceptibility in Epoxy/Magnetite Nanocomposites

The epoxy/magnetite nanocomposites express superparamagnetism under a static or low-frequency electromagnetic field. At the microwave frequency, said the X-band, the nanocomposites reveal an unexpected diamagnetism. To explain the intriguing phenomenon, we revisit the Debye relaxation law with the memory effect. The magnetization vector of the magnetite is unable to synchronize with the rapidly changing magnetic field, and it contributes to diamagnetism, a negative magnetic susceptibility for nanoparticles. The model just developed and the fitting result can not only be used to explain the experimental data in the X-band but also can be used to estimate the transition frequency between paramagnetism and diamagnetism.

cond-mat.mes-hall↗