We report the temperature-dependent evolution of Raman spectra of monolayer WS₂ directly CVD-grown on a gold foil and then transferred onto quartz substrates over a wide temperature range from 84 to 543 K. The nonlinear temperature dependence of Raman shifts for both "Equation missing"<!-- image only, no MathML or LaTex --> and A_1g modes has been observed. The first-order temperature coefficients of Raman shifts are obtained to be −0.0093 (cm⁻¹/K) and −0.0122 (cm⁻¹/K) for "Equation missing"<!-- image only, no MathML or LaTex --> and A_1g peaks, respectively. A physical model, including thermal expansion and three- and four-phonon anharmonic effects, is used quantitatively to analyze the observed nonlinear temperature dependence. Thermal expansion coefficient (TEC) of monolayer WS₂ is extracted from the experimental data for the first time. It is found that thermal expansion coefficient of out-plane mode is larger than one of in-plane mode and TECs of "Equation missing"<!-- image only, no MathML or LaTex --> and A_1g modes are temperature-dependent weakly and strongly, respectively. It is also found that the nonlinear temperature dependence of Raman shift of "Equation missing"<!-- image only, no MathML or LaTex --> mode mainly originates from the anharmonic effect of three-phonon process, whereas one of A_1g mode is mainly contributed by thermal expansion effect in high temperature region, revealing that thermal expansion effect cannot be ignored.

Static and dynamic hysteresis loops of TbFeCo amorphous films are measured by vibrating sample magnetometry (VSM) and magneto-optical Kerr rotation. The static VSM loop shows a faster magnetization reversal than the static Kerr loop does. The dynamic Kerr hysteresis loop in a sinusoidal alternating magnetic field at $1.14\mathrm{kHz}$ shows a large increase in coercivity with respect to the static coercivity. The ultrafast dynamics of laser-induced demagnetization and magnetization recovery is studied by femtosecond time-resolved polar Kerr rotation spectroscopy, and shows a subpicosecond demagnetization and several hundreds of picosecond magnetization recovery process, which suggests gigahertz writing rate possible.

The effects of a titanium dopant on the phase transition behavior and crystallization mechanism of Ge₈Sb₉₂ films were systematically investigated.

Tellurium-free Ti_xSb_100−x phase-change materials were systematically investigated. The amorphous-to-crystalline transition was studied by in situ resistance measurements. The crystallization temperature, crystalline resistance, and optical bandgap of Ti_xSb_100−x thin films were enhanced significantly with the increase in the titanium concentration. The phase structure and microstructure were confirmed by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM), respectively. The chemical state of the elements was detected by X-ray photoelectron spectroscopy (XPS). The phase transition speed between the amorphous and crystalline states was obtained by picosecond laser pulses. Phase change memory cells based on the Ti₂₇Sb₇₃ thin film were fabricated to evaluate the electrical characteristics as well. The results indicate that the Ti_xSb_100−x thin films have the great potentiality in phase change memory applications.