Terahertz time-domain signatures of the inverse Edelstein effect in topological-insulator/ferromagnet heterostructures
Abstract
Three-dimensional topological insulators possess topologically protected surface states with spin-momentum locking, which enable spin-charge-current interconversion (SCI) by the inverse Edelstein effect (IEE). However, it remains experimentally challenging to separate the surface-related IEE from the bulk-type inverse spin Hall effect (ISHE). Here we search for distinct time-domain signatures of the two SCI phenomena in an ℱ/TI model stack of a ferromagnetic-metal layer ℱ (Co and Fe) and a topological-insulator (TI) layer (Bi₂Te₃, SnB₂Te₄, and Bi1-xSbx with = 0.15 and = 0.3), where the focus is on Bi₂Te₃. A femtosecond laser pulse serves to induce a transient spin voltage μsℱ in ℱ and, thus, drive an ultrafast spin current out of F . SCI results in a transverse charge current with a sheet density Ic that is detected by sampling of the emitted terahertz electric field. Analysis of the dynamics of Ic(t) vs time relative to μsℱ(t) reveals two components with distinct timescales: (1) a quasi-instantaneous response and (2) a longer-lived response with a relaxation time of 270 fs, which is independent of the ℱ material chosen. Component (1) is consistently ascribed to the ISHE. In contrast, we interpret component (2) as a signature of interfacial spin accumulation and the IEE at the ℱ/ Bi₂Te₃ interface, with a fraction of less than 10 − 2 of the incident spins participating. This assignment is fully consistent with respect to its dynamics and magnitude. We rate other possible signal contributions, such as spin trapping in intermediate states, as less likely. Our results show that the femtosecond dynamics of photocurrents allow us to differentiate the ISHE and the IEE and, more generally, provide important insights into the mechanisms of spin transport and SCI in ℱ/TI stacks.
Related
- Anomalous spin-pumping behavior of half-metallic ferromagnet/d-wave superconductor heterostructures
- Direct Quantification of Molecular Helicity-Dependent Effective Magnetic Fields in Chiral Polypeptide/Ferromagnet Heterostructures
- Quantitative Disentanglement of Terahertz Spin and Orbital Pumping in 3d Ferromagnetic Heterostructures
- Optimizing spin-based terahertz emission from magnetic heterostructures
- Electronic and topological properties of Ce-based honeycomb ferromagnet Ce2Zn6Ge3
BibTeX
@article{bierhance2026terahertz,
title = {{Terahertz time-domain signatures of the inverse Edelstein effect in topological-insulator/ferromagnet heterostructures}},
author = {G. Bierhance and C. In and E. Rongione and R. Rouzegar and O. Gueckstock and E. Longo and L. Baringthon and N. Reyren and R. Lebrun and J.-M. George and P. Tsipas and M. Wolf and T.S. Seifert and R. Mantovan and H. Jaffrès and A. Dimoulas and T. Kampfrath},
journal = {Physical Review Applied},
year = {2026},
month = sep,
doi = {10.1103/n1nw-2wyg},
url = {https://hal.science/hal-05764189v1},
note = {CC BY-SA 4.0},
}
RIS
TY - JOUR
TI - Terahertz time-domain signatures of the inverse Edelstein effect in topological-insulator/ferromagnet heterostructures
AU - G. Bierhance
AU - C. In
AU - E. Rongione
AU - R. Rouzegar
AU - O. Gueckstock
AU - E. Longo
AU - L. Baringthon
AU - N. Reyren
AU - R. Lebrun
AU - J.-M. George
AU - P. Tsipas
AU - M. Wolf
AU - T.S. Seifert
AU - R. Mantovan
AU - H. Jaffrès
AU - A. Dimoulas
AU - T. Kampfrath
PY - 2026
DA - 2026/09/25
JO - Physical Review Applied
DO - 10.1103/n1nw-2wyg
UR - https://hal.science/hal-05764189v1
AB - Three-dimensional topological insulators possess topologically protected surface states with spin-momentum locking, which enable spin-charge-current interconversion (SCI) by the inverse Edelstein effect (IEE). However, it remains experimentally challenging to separate the surface-related IEE from the bulk-type inverse spin Hall effect (ISHE). Here we search for distinct time-domain signatures of the two SCI phenomena in an ℱ/TI model stack of a ferromagnetic-metal layer ℱ (Co and Fe) and a topological-insulator (TI) layer (Bi₂Te₃, SnB₂Te₄, and Bi1-xSbx with = 0.15 and = 0.3), where the focus is on Bi₂Te₃. A femtosecond laser pulse serves to induce a transient spin voltage μ_s^ℱ in ℱ and, thus, drive an ultrafast spin current out of F . SCI results in a transverse charge current with a sheet density Ic that is detected by sampling of the emitted terahertz electric field. Analysis of the dynamics of Ic(t) vs time relative to μ_s^ℱ(t) reveals two components with distinct timescales: (1) a quasi-instantaneous response and (2) a longer-lived response with a relaxation time of 270 fs, which is independent of the ℱ material chosen. Component (1) is consistently ascribed to the ISHE. In contrast, we interpret component (2) as a signature of interfacial spin accumulation and the IEE at the ℱ/ Bi₂Te₃ interface, with a fraction of less than 10 − 2 of the incident spins participating. This assignment is fully consistent with respect to its dynamics and magnitude. We rate other possible signal contributions, such as spin trapping in intermediate states, as less likely. Our results show that the femtosecond dynamics of photocurrents allow us to differentiate the ISHE and the IEE and, more generally, provide important insights into the mechanisms of spin transport and SCI in ℱ/TI stacks.
SN - 2331-7019
ER -