Speaker
Description
Antiferromagnetic (AF) spintronics offers a promising route towards more efficient and stable devices, because antiferromagnets are less susceptible to external fields and foster a broad range of magnetic interactions with the potential for higher speeds and energy efficient manipulation. In particular, light-induced control of the AF state has been recently demonstrated, and the use of ultrashort femtosecond light pulses opens the path towards ultrafast AF dynamics. However, the microscopic understanding of AF magnetization dynamics and its relation to the fundamental exchange pathways in a material are so-war not well understood, in particular in technologically-relevant 4f materials with indirect (RKKY) exchange interaction.
Time-resolved resonant x-ray diffraction (trRXD) has been established as a technique to directly probe the ultrafast dynamics of long-range antiferromagnetic ordering. The resonant enhancement at the L2/3 or M4/5 edges provides direct sensitivity to the magnetically ordered 3d or 4f states, alongside with element sensitivity. We have applied this technique to study the ultrafast magnetization dynamics in a series of 4f intermetallic materials of the type LnRh2Si2 (with Ln = lanthanide). This series of nearly-identical AF materials allows to study the influence of varying indirect exchange interaction on the magnetization dynamics through the replacement of Ln ions, where we find a variation from 100s of fs to 100s of ps [1]. A systematic comparison with theory reveals that the angular momentum transfer rate between opposite spin sublattices is directly determined by the magnitude of the indirect RKKY exchange. Furthermore, we discuss the influence of replacing the transition metal in the Gd-based compounds GdTm2Si2 with Tm=Co,Rh,Ir, which modifies the conduction electron contribution to the RKKY interaction. Comparison to time-resolved photoemission data additionally allows us to systematically study the energy transfer between the electronic, spin and lattice subsystems.
References
[1] Y.W. Windsor et al., Nature Mater. 21, 514 (2022).
| Abstract Number (department-wise) | PC 05 |
|---|---|
| Department | PC (Wolf) |
