General Topic: Ultrafast dynamical processes in condensed matter systems using femtosecond laser pulses. In 1996 J.-Y. Bigot pioneered the field of Femtomagnetism (PRL., 76, 4250 (1996)).
- Femtomagnetism (or Ultrafast Magnetization Dynamics): Magnetization dynamics of ferromagnetic metal films and nanoparticles (superparamagnetism) induced and studied by femtosecond laser pulses.
- Nanophotonics: Time resolved optical studies of individual and/or assemblies of metallic nanostructures.
- Spin Photonics: Study of magnetic devices using Kerr and Faraday magneto-optical microscopy. Some works are related to Spintronics and Heat assisted Magnetic Recording.
- Coherent molecular motion: Time resolved coherent vibrational processes of polymers and metallic nanostructures.
- Theoretical investigation of the time dependent magneto-optical response: Landau-Lifschitz-Gilbert formalism + temperature dependent effective field (two-temperature model); Dirac equation combined with time dependent nonlinear response using density matrix formalism.
Laser systems and techniques used in my team Femtomag at IPCMS:
Femtosecond laser sources:
5 kHz, 2W, 800 nm, 45 fs
10 kHz, 10W, tunable 400-900 nm with visible Optical Parametric Amplifier (OPA), 30 fs
1 kHz, 10W, tunable 1-2.5 µm with infrared OPA, 25 fs
High Harmonic Generation table-top source (20-70 eV) at 1 kHz, 100 fs
Ti:S oscillator 10 fs at 80 MHz
100 Hz, 150 mJ/pulse, 25 fs at 800 nm.
We also have collaborated with the “Femtoslicing” beam line at BESSY synchrotron (Germany) in 2010. L2 and L3 edges of Cobalt (778-793 eV).
Measurement techniques mastered:
Pump-probe spectroscopy (visible, near IR, extreme UV probe, Xrays probe)
Time resolved magneto-optical Kerr and Faraday
Magneto-optical Kerr/Faraday microscopy (spatial and temporal resolutions: 300 nm, 120 fs)
Femtosecond Four Wave Mixing: two and three beams configurations
Transport properties in sub-micron nanostructures
Cryogenic magnetic measurements: 10 T, 1.5 K supra-conducting magnet designed for pump (800-400 nm) and probe (supercontinuum: 480-700 nm) Kerr and Faraday spectroscopy
High Harmonic Generation and Xray detection in pump probe configuration
Picosecond Magneto-acoustics generation and use in pump-probe configurations.