ATTOCALMAT

Atto-calorimetric tools to explore material properties in the nanoscale

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 Obiettivo del progetto (Objective)

'Nanoscale phenomena where the surface/interfaces or the small dimensions play a predominant role in the physical properties have become increasingly important in the last decade. Many characterization techniques have been adapted to face new challenges and understand new phenomena and calorimetry is no exception. ATTOCALMAT project pursues the development of a new nanocalorimetric technique the ’microsecond-pulsed steady-state method’ that will combine the signal enhancing of the fast scanning and the advanced signal averaging of steady-state techniques. Preliminary results with sensitivities of 5 pJ/Kmm have already shown an improvement by a factor of 50 compared to the best steady state techniques. With the scaling down of the Si-nanochips (sensing areas~200 nm^2), the addenda reduces to few fJ/K. The increase of surface selectivity is followed by the sensitivity with values of 0.2 aJ/K. Chips with a monocristalline Si layer below the SiNx membrane will easy the study of epitaxial materials. With the new cutting edge technique and the nanochip measurement of heat capacities of single nano-objects as function of temperature but also of external variables (like magnetic and electrical field, time…) are within reach. This thermal tool will be applied to underpinning the physical properties of materials that represent a leading edge research frontier in nanoscale science towards its end-use in potential applications as magnetic storage, spintronics or photonics. Several of the challenging and unexplored measurements proposed are: (i) Magnetocalorimetry to detect Néel’s wall formation in the antiferromagnetic material of an exchange biased system on physical properties. (Co/CoO or Ni/NiO) (ii) Measurements of energy involved on the 2D-3D transition of Ge epitaxial heteroestructure on Si. (iii) Nanocalorimetric study of low dimensionality effects in the ferromagnetic transition of epitaxial EuO on Si.'

Introduzione (Teaser)

Nanomaterials exhibit unique electrical, magnetic and thermal functionalities that are of great interest to engineers. Improved ability to measure miniscule thermal changes in nanomaterials during chemical processes will foster novel device designs.

Descrizione progetto (Article)

To measure the very small heat capacities (thermal energies required to change the temperatures) of nanomaterials, improved calorimetry is required.

The EU-funded project 'Atto-calorimetric tools to explore material properties in the nanoscale' (ATTOCALMAT) was initiated to deliver a tool for thermal measurements on small scales. The developed technique, called the microsecond-pulsed steady-state nanocalorimetry method, combines the signal enhancement of fast scanning with advanced signal averaging of steady-state techniques. Ultra-fast heating rates are key to high resolution and signal averaging takes care of measurement anomalies.

Scientists sought to exploit it for the nanochip measurement of heat capacities of single nano-objects with respect to temperature, applied electrical or magnetic fields and time. The latter dependencies are of critical importance to the development of new magnetic storage, spintronics or photonics devices.

ATTOCALMAT developed an experimental measurement setup with newly designed nanocalorimeters and a superconducting coil for generating magnetic fields. The new calorimeters have reduced sensing areas to increase selectivity. The instrumentation is synchronised such that the background pulsed heating is executed while external variables such as magnetic field, gas pressure and temperature are controlled. The setup is an important project contribution to analysis of size effects on heat capacity.

Researchers successfully applied the new experimental setup to the study of the interface reaction between palladium, nickel and silicon to form silicides. Silicides are two-element compounds in which one is silicon. They also conducted simultaneous nanocalorimetric and synchrotron radiation experiments yielding important insight into mechanisms of formation of the silicide phase.

Further optimisation and realisation of the complete pulse-heating, small-area devices will facilitate important new measurements of small-scale heat changes during chemical processes. Such measurements will enable scientists and engineers to produce knowledge-based designs for new devices in fields including magnetic storage, spintronics and photonics.