Multidetection scheme for transient-grating-based spectroscopy

Time-resolved optical spectroscopy represents an effective non-invasive approach to investigate the interplay of different degrees of freedom, which plays a key role in the development of novel functional materials. Here, we present magneto-acoustic data on Ni thin films on SiO₂ as obtained by a versatile pump-probe setup that combines transient grating spectroscopy with time-resolved magnetic polarimetry. The possibility to easily switch from a pulsed to continuous wave probe allows probing of acoustic and magnetization dynamics on a broad time scale, in both transmission and reflection geometry.

An integrated ultra-high vacuum apparatus for growth and in situ characterization of complex materials

Here, we present an integrated ultra-high vacuum apparatus-named MBE-Cluster -dedicated to the growth and in situ structural, spectroscopic, and magnetic characterization of complex materials. Molecular Beam Epitaxy (MBE) growth of metal oxides, e.g., manganites, and deposition of the patterned metallic layers can be fabricated and in situ characterized by reflection high-energy electron diffraction, low-energy electron diffraction, Auger electron spectroscopy, x-ray photoemission spectroscopy, and azimuthal longitudinal magneto-optic Kerr effect. The temperature can be controlled in the range from 5 K to 580 K, with the possibility of application of magnetic fields H up to ±7 kOe and electric fields E for voltages up to ±500 V. The MBE-Cluster operates for in-house research as well as user facility in combination with the APE beamlines at Sincrotrone-Trieste and the high harmonic generator facility for time-resolved spectroscopy.

Quantifying the critical thickness of electron hybridization in spintronics materials

In the rapidly growing field of spintronics, simultaneous control of electronic and magnetic properties is essential, and the perspective of building novel phases is directly linked to the control of tuning parameters, for example, thickness and doping. Looking at the relevant effects in interface-driven spintronics, the reduced symmetry at a surface and interface corresponds to a severe modification of the overlap of electron orbitals, that is, to a change of electron hybridization. Here we report a chemically and magnetically sensitive depth-dependent analysis of two paradigmatic systems, namely La_1−xSr_xMnO₃ and (Ga,Mn)As. Supported by cluster calculations, we find a crossover between surface and bulk in the electron hybridization/correlation and we identify a spectroscopic fingerprint of bulk metallic character and ferromagnetism versus depth. The critical thickness and the gradient of hybridization are measured, setting an intrinsic limit of 3 and 10 unit cells from the surface, respectively, for (Ga,Mn)As and La_1−xSr_xMnO₃, for fully restoring bulk properties.

Surface versus bulk effects in electronic structure of spintronics materials are crucial to their applications but are yet well understood. Here the authors experimentally determine the critical thickness that defines the crossover of electron hybridization between surface and bulk for two prototype spintronics materials.

Spectroscopic identification of the chemical interplay between defects and dopants in Al-doped ZnO

Contributions to the spectroscopic response of defects and dopants in Al-doped ZnO films are determined combining X-ray spectroscopies and DFT.

Magnetic gas sensing exploiting the magneto-optical Kerr effect on ZnO nanorods/Co layer system

A new system based on a Co film covered by ZnO nanorods has been fabricated with sputtering technique. It represents a promising candidate for future generation of magnetic gas sensing devices.

New strategy for magnetic gas sensing

New strategy for room temperature magnetic gas sensing based on magnetoelectrically-coupled hybrids. The sensor is sensitive, fast and cost-effective. The sensing is allowed thanks to the magneto-electric coupling at the interface.