Joint Laboratory of Optospintronics


Joint Opto-Spintronics laboratory is formed by femtosecond Ti:sapphire laser (Mai Tai HP, Spectra Physics) supplemented by optical parametric oscillator (Inspire HF, Spectra Physics) that provide a gap-free tuneability of femtosecond laser pulses from 350 nm (3.5 eV) to 2.2 µm (0.56 eV) at a repetition rate of 82 MHz; the repetition rate can be reduced down to single pulse using a pulse picker.

The sample can be placed in a closed-cycle helium cryostat (Advanced Research Systems), with a temperature range 10-800 K, that has an extremely low level of sample vibrations (tens of nm) and that is equipped by 18 wires for standard transport/electrical experiments, and 1 microwave cable for electrical experiments with frequencies up to 50 GHz, which enables us to combine optical and electrical experiments in devices.

The time-resolved measurements can be performed using various techniques of ultrafast laser spectroscopy: pump-probe (a measurement of transient absorption and reflection), time-resolved magneto-optical Kerr effect (TR MOKE), time-resolved photoluminescence, and laser-induced dynamic grating experiment (four-wave-mixing). These experiments can be performed with a simultaneous high spatial- (sub-micrometer) and time- (sub-picosecond) resolutions. Measurements of various linear and quadratic magneto-optical effects (magnetic circular dichroism, MCD, and birefringence, MCB, magnetic linear dichroism, MLD, and birefringence, MLB, with a simultaneous spatial- and spectral-resolutions can be performed in a home-made experimental setup that includes the closed-cycle helium cryostat and electromagnet (Walker Scientific, model HV-4H), which is generating magnetic field up to 1.5 T. The THz lab has custom-made time-domain THz spectroscopy setups (0.15-3 THz, 5-950 K, 0-7 T) based on femtosecond laser oscillators (Coherent, Mira, Vitesse) and multi-THz air-based photonics (1-23 THz) powered by a femtosecond amplifier (Spectra-Physics, ACE). Additionally, the laboratory has a THz-SNOM (0.1-3 THz) with 30 nm resolution and with a pump-probe measurement option.

Joint Laboratory of Optospintronics

Faculty of Mathematics and Physics
Charles University
Ke Karlovu 5, 121 16 Praha 2

Head of Laboratory: Doc. RNDr. Petr Němec, PhD (e-mail: nemec [at] karlov [dot] mff [dot] cuni [dot] cz)

Contact Person: prof. Tomáš Jungwirth, PhD.