Mapping spin-correlations with hard X-ray free-electron laser

Yinpeng Zhong,Mariano Trigo,Joachim Ullrich,Lutz Foucar,Iime Schlichting,Chen Jian,Hailong Wang,Diling Zhu,David Reis,Sascha Epp,Henrik Lemke,Jianhua Zhao,Faton Krasniqi,G Cerullo,M Khalil,J Ogilvie,R Li,F Kärtner

doi:10.1051/epjconf/201920507007

Abstract

Time-resolved X-ray diffraction from Ga091Mn0 09As was recorded with a hard X-ray free-electron-laser. The influence of spin-orders on phonons was investigated; our result suggests a new method for mapping the spin-correlations in low doped magnetic systems, especially the short-range spin-correlation.

Highlights

Ultrafast dynamics of the spin-correlation in ferromagnets were recently revealed by the time-resolved soft X-ray diffraction (XRD) at free electron laser sources [1,2]
In the magnetic system they studied, spin-obit coupling leads to energy degeneracy modulates soft XRD intensity which reflects the dynamics of the spin orders
In other magnetic systems, such as diluted magnetic semiconductors (DMS) [3], the ferromagnetism originates from doped magnetic atoms, due to the low doping level, the distance between the Mn atoms is too large to form direct spin-spin interaction; but rather have to be mediated by the freely moving holes

Summary

Introduction

Ultrafast dynamics of the spin-correlation in ferromagnets were recently revealed by the time-resolved soft X-ray diffraction (XRD) at free electron laser sources [1,2]. In the magnetic system they studied, spin-obit coupling leads to energy degeneracy modulates soft XRD intensity which reflects the dynamics of the spin orders. The low doping levels typically provides weak signals and the random allocation of the magnetic atoms destroys the diffraction coherence. Soft XRD methods are limited; further, it cannot distinguish the longrange and short-range spin-correlations. In this contribution, we demonstrate a timeresolved hard XRD method for mapping spin correlations.

Experimental method

Results