Tuning the Ultrafast Spin Dynamics in Carrier-Density-Controlled Ferromagnets

TL;DR

This paper demonstrates ultrafast control of ferromagnetic order in Eu1-xGdxO using resonant photoexcitation, revealing the role of carriers in nonequilibrium spin dynamics and providing design criteria for spintronics materials.

Contribution

It introduces a novel approach to manipulate ferromagnetic order on ultrafast timescales and offers a theoretical framework beyond the three-temperature model for spin dynamics.

Findings

Magnetic order can be strengthened or quenched within 3 ps.

Carrier interplay governs the ultrafast magnetic response.

Provides design criteria for tunable spintronics materials.

Abstract

Ultrafast strengthening or quenching of the ferromagnetic order of semiconducting Eu1-xGdxO was achieved by resonant photoexcitation. The modification of the magnetic order is established within 3 ps as revealed by optical second harmonic generation. A theoretical analysis shows that the response is determined by the interplay of chemically and optically generated carriers in a nonequilibrium scenario beyond the three-temperature model. General criteria for the design of spintronics materials with tunable ultrafast spin dynamics are given.