Brillouin Light Scattering

Electronic & Chemical & Magnetic Characterization (Optical spectroscopy)

Three Brillouin Light Scattering (BLS) experimental setups are available:

1) Conventional Brillouin light scattering (BLS) setup, which allows BLS measurements from thermally excited spin waves in the frequency range between 1 and 200 GHz and a spatial resolution of 30 um. Possibility to apply static magnetic field up to 2 T parallel to the sample surface and to change the incidence angle of light with respect to the sample normal. This allows to explore a wave vector range from 0 to2.2x10^7 rad/m and to measure the dispersion of spin waves (frequency vs wave-vector). Azimuthal rotation of the sample around its normal is also possible to investigate the presence of in-plane magnetic anisotropy.

2) Micro-focused Brillouin light scattering with a lateral resolution down to about 250 nm intensity of the applied magnetic field up to 1 T (out-of-plane) and 0.25 t in-plane. This technique allows to perform 1D and 2D spatial maps of the spin-wave intensity generated by either dc current or a microwave current (up to 20 GHz).

3) Combined micro-Brillouin and micro-Raman set-up to observe collective dynamics (mechanical characterization) by BLS and high frequency molecular vibrational modes (chemical characterization) by Raman in a variety of samples with u-metric spatial resolution (Lateral spatial resolution 500 nm up to 2 um). Frequency resolution: in Brillouin spectra 100 MHz, in Raman spectra 2 cm^(-1)). Laser source at 532 nm. The temperature range covers from -195°C to 300°C. Plus supporting equipment, such as an Atomic Force Microscope operating both in contact and tapping mode and capable of Magnetic force microscopy measurements, and a magneto-optic kerr effect magnetometry apparatus with photo-elastic modulator operating at 50 kHz and lock-in amplification, for measuring hysteresis loops of magnetic nanostructures in the longitudinal configuration and maximum applied field of 200 mT.

          provided by:
Brillouin Light scattering spectroscopy from spin waves
Study of the spin waves excitation in low dimensional ferromagnetic nanostructures
Single mode laser operating at 532 nm
Frequency range: 0-200 GHz Magnetic field range up to 2 T (on 3mm poles gap) Wavevector range: 0- 2.2 10^7 m^-1
0.1 GHz
30-40 microns
3D translational stage Incidence angle of light (θ) from 0 to 90 degrees (Explored wave vector range from 0 to 2.2x10^7 rad/m) Azimuthal angle (φ) from 0 to 360 degrees
Maximum dimensions 1x1 cm^2 Room temperature
Reversable magnetic field applied in the sample plane up to 1.5 T for Magnetostatic surface configuration (Damon-Eshbach geometry) and 0.2 T in the backward configuration.
Optical microscope to find patterned areas prepared on the same substrate
200 mW, single-frequency, Excelsior Diode-Pumped Solid-State (DPSS) laser, operating in the spectral line of 532 nm, with a line width of approximately 10 MHz. Power on the sample about 10 mW
250 nm
A nanoposition stage allows to position the sample with a precision down to 10 nm on all three axes.
Room temperature
In-plane magnetic field of 0.25 T Field projected out-of-plane of 1T
A coaxial viewing system based on a collimated LED light source (455 nm wavelength), a beam expander, and a CCD camera is used to obtain a direct visualization of the laser spot and of the sample region under investigation.
6220 Keithley precision current source 2182A Leithley nanovoltmeter Agilent EXA N9010A Signal Analyzer 10 Hz-26.5 GHz Agilent E8257D Analog Signal Generator 250 kHz-20 GHZ
Combined micro-Brillouin and micro-Raman set-up
Mechanical characterization at the microscale
laser at 532 nm P=100mW
-80 to 80 GHz
100 MHz
1 um
(x,y,z) inverted microscope range (1cm,1 cm,1 cm) with a step of 1 um
A coaxial viewing system based on a white LED light source, a beam expander, and a CCD camera is used to obtain a direct visualization of the laser spot and of the sample region under investigation.
Combined Brillouin and Raman spectroscopy