Ultrafast control of magnetism with twisted plasmons

Introduction

Harnessing twisted light (light carrying orbital angular momentum) on the nanoscale, and its interaction with magnetism, can revolutionize how we encode and process information. In fact, twisted electromagnetic fields can enable superior control over the motion of the electrons and their spin compared to circularly polarized light.

Challenge

Yet, a clear demonstration that it is possible to act on magnetism using twisted light has still to be established. The main challenge is to find an approach to generate nanoscale electromagnetic fields carrying orbital angular momentum, which can be exploited to drive magnetism with extreme (few nanometers) spatial resolution, at the intrinsic time scale (few tens of femtoseconds) of the fundamental magnetic interactions (exchange and spin-orbit coupling) responsible for the magnetic order in matter.

Importance

This feature is essential for the development of ultrafast opto-magnetic applications in spintronics, where a major goal is the coherent control of nanoscale magnetic bits.

Proposed Solution

In MagneticTWIST, I tackle this challenge and propose the way towards nanoscale control of ultrafast magnetic phenomena by exploiting twisted plasmons, that is, plasmon polaritons (light-induced coherent collective oscillations of free electrons in metals) carrying orbital angular momentum and driven by femtosecond light pulses.

Expected Outcomes

This strategy will enable a coherent transfer of orbital angular momentum to the electronic spin and orbital degrees of freedom at the nanoscale. In this way, I will disclose new types of light-matter interactions and new kinds of opto-magnetic effects, with a ground-breaking impact on ultrafast magnetism, spintronics, and light-driven electronics.

Broader Impact

Beyond this, MagneticTWIST will open a radically new path enabling the storage and processing of an infinite amount of information on different spatiotemporal levels, impacting also other research fields such as cryptography, artificial intelligence, and quantum technology.