Petahertz Spintronics

TL;DR

This paper demonstrates ultrafast magnetic switching at sub-femtosecond timescales using near-single-cycle laser pulses, revealing a new regime of light-controlled spin dynamics with potential for Petahertz spintronic applications.

Contribution

It introduces a novel attosecond magnetic circular dichroism technique and uncovers a coherent, non-dissipative mechanism for controlling spin dynamics at petahertz frequencies.

Findings

Achieved sub-femtosecond magnetic switching.

Observed real-time spin and orbital momentum transfer.

Demonstrated coherent control of spin dynamics with light fields.

Abstract

The enigmatic coupling between electronic and magnetic phenomena was one of the riddles propelling the development of modern electromagnetism. Today, the fully controlled electric field evolution of ultrashort laser pulses permits the direct and ultrafast control of electronic properties of matter and is the cornerstone of light-wave electronics. In sharp contrast, because there is no first order interaction between light and spins, the magnetic properties of matter can only be affected indirectly on the much slower tens-of-femtosecond timescale in a sequence of optical excitation followed by the rearrangement of the spin structure. Here we record an orders of magnitude faster magnetic switching with sub-femtosecond response time by initiating optical excitations with near-single-cycle laser pulses in a ferromagnetic layer stack. The unfolding dynamics are tracked in real-time by a novel attosecond time-resolved magnetic circular dichroism (atto-MCD) detection scheme revealing optically induced spin and orbital momentum transfer (OISTR) in synchrony with light field driven charge relocation. In tandem with ab-initio quantum dynamical modelling, we show how this mechanism provides simultaneous control over electronic and magnetic properties that are at the heart of spintronic functionality. This first incarnation of attomagnetism observes light field coherent control of spin-dynamics in the initial non-dissipative temporal regime and paves the way towards coherent spintronic applications with Petahertz clock rates.