Controlling spin angular momentum with the field of light

Project Information

SPINFIELD

Grant agreement ID: 101041074

DOI

10.3030/101041074

EC signature date 1 March 2022

Start date 1 October 2022

End date 30 September 2027

Funded under

• European Research Council (ERC)

Total cost

€ 1 499 625,00

EU contribution

€ 1 499 625,00

Coordinated by

COMMISSARIAT A L ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
France

Periodic Reporting for period 1 - SPINFIELD (Controlling spin angular momentum with the field of light)

Reporting period: 2022-10-01 to 2025-03-31

Summary of the context and overall objectives of the project

This project is aimed at the study of solids using attosecond laser pulses, the shortest pulses of light available today. These pulses, which operate in the extreme ultraviolet range of the electromagnetic spectrum, allow to probe ultrafast electron dynamics in materials at extremely short timescales. Attosecond spectroscopy has emerged as a cutting-edge field in recent years, opening new avenues for understanding the fundamental behaviors of electrons in condensed matter systems.

Here, we set to explore the interaction between light the spin of electrons. The electron spin is an intrinsic quantum property that plays a crucial role in determining the macroscopic physical characteristics of materials, including magnetism. The goal of this research is to address a fundamental, yet unresolved question: do electron spins in solids interact directly and coherently with the electric field of light? The possibility of such a direct coupling between the spin of an electron and the oscillating electric field of light is a completely open and intriguing question at this stage. To address this problem, we leverage the progresses of attosecond science and state-of-the-art instrumentation. The combination of attosecond pulses with advanced detection techniques will allow for the ultrafast measurement of spin dynamics with increased precision, with the aim to isolate and observe these elusive spin-field interactions.

The potential impact of this research extends beyond fundamental physics. Understanding how electron spins interact with light fields could open new possibilities for controlling material properties in ways that were previously unattainable. For instance, if spin-field interactions can be manipulated coherently, it may be possible to use laser pulses to control the magnetization of materials on ultrafast timescales. This capability could be used in spintronics, a field of research focused on using electron spin rather than charge to develop next-generation electronic devices. Spintronics has already shown promise for creating faster and more energy-efficient memory storage technologies, and the ability to control spin with light could further enhance its potential applications.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first two years of the project, we were able to develop an original experimental apparatus for attosecond transient absorption of solids, using a new laser source based on an ytterbium gain medium. This has involved significant development and implementation of post-compression techniques, in order to get ultrashort pulses lasting only a few optical cycles. One activity has been the installation of an entirely set of vacuum chambers and of a new spectrometer to perform the planned experiments. Preliminary measurements show that the new apparatus has largely increased stability and reliability compared to the state-of-the-art, which directly translates into an significant increase in its detection sensitivity. Thus, this constitutes a key technical advance that will now put us in an advantageous position to explore spin-field interactions in magnetic materials.
In parallel, we worked with other laboratories to develop attosecond magnetic circular dichroism using existing beamlines. We were able to demonstrate that short light pulses can trigger very short spin injection between layers in spintronic structures.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The technical developments performed during the project have the potential to contribute to new generations of attosecond apparatus with better sensitivity and reliability. This will be confirmed by ongoing experiments on materials, which we hope will result in new understanding of ultrafast dynamics of electron charges and spins in complex materials.