Ultra-fast spin accumulations make it possible to reverse the magnetisation in magnetic materials
Researchers have identified a mechanism governing the interaction between magnetism and laser-induced spin clusters in a multilayer material, paving the way for an ultra-fast magnetic memory writing mechanism.
References
Ultrafast Spin Accumulations Drive Magnetization Reversal in Multilayers, Harjinder Singh, Alberto Anadón, Junta Igarashi, Quentin Remy, Stéphane Mangin, Michel Hehn, Jon Gorchon, Gregory Malinowski, Physical Review Letters 136, 056701 - Published 2 February, 2026.
DOI: 10.1103/z2sz-2tdz
Open Access: arXiv
The ultra-fast control and manipulation of local magnetic states within matter is a key challenge for information technology, in a world where the demand for data storage and processing is growing exponentially. A particularly promising avenue in this field is spintronics, a technology that aims to exploit not only the charge of electrons, but also their spin (a quantum property that causes them to behave like tiny magnets).
The present study was carried out in the following CNRS laboratory:
- Institut Jean Lamour (IJL, CNRS/Université Lorraine)
In a recent study, researchers have succeeded in controlling the magnetisation of a material using light. They used ultra-short laser pulses (on the order of a femtosecond, or one millionth of a billionth of a second) to generate and detect spin accumulations within a layer of copper, a naturally non-magnetic material. To make this possible, the researchers fabricated structures containing two magnetic layers separated by a copper layer and excited and probed these assemblies with laser beams. In previous work, they had demonstrated that in these structures, ultra-fast heat input via the laser was capable of reversing the magnetisation of one of the magnetic layers in less than 1,000 femtoseconds – a way of writing information extremely quickly into a memory. In this new work, the researchers show that in these same structures, significant spin accumulations are generated in the copper following the heating and cooling of the magnetic layers. These accumulations subsequently affect the magnetic orientation of the layers and manage to reverse the magnetisation of one of the layers. To uncover these mechanisms, the researchers have developed an innovative optical method in recent years for detecting spin accumulations on ultra-fast timescales. The techniques developed by the team make it possible, for the first time, to independently detect the dynamics of magnetisation and those of spin accumulations in complex multilayer systems. This work provides a better understanding of how spins accumulate and interact with the magnetisation of the magnetic layers in these systems. The mechanisms discovered allow magnetisation to be manipulated much more rapidly than with current technologies, paving the way for ultra-fast computer memories or sensors. These results are published in the Physical Review Letters.
