Laser stimulated kinetics effects on the phase transition of the ferromagnetic/superconducting MgB2/(CrO2) bilayer thin films

• Photoinduced enhancement of critical temperature in MgB2–Cr2O3 films was found.
• Crucail role of electron–phonon interacton was shown.
• Optimal ratio fundamental/SHG intensities was varied within 4:1 and 6:1.

Using bicolor laser treatment by Nd:YAG 20 ns laser (1064–532 nm) and 180 ns CO2 laser beams (10.6–5.3 μm) it was shown a possibility of critical temperature enhancement in ferromagnetic superconducting MgB2/CrO2 bilayer films. The role of the phonon sub-system effectively interacting with 3d Cr originating localized trapping levels is discussed. The pump–probe laser kinetics for the probing second harmonic generation at 1064 nm is explored in details to show principal role of the localized trapping levels. The relaxation of the processes after the switching off the photo inducing beams show the disappearance of the enhanced superconductivity after the 20–30 s. The temperature dependence of the resistance show nonlinear dependence versus the pumping power and different optimal fundamental to writing power density beams ratio.

Dependence of resistance versus temperature for different power densities. The nonzero value is generated from the bottom CrO2 resistive layer. The onset transition temperature is our reference for the enhancement value.Figure optionsDownload as PowerPoint slide