Giant enhancement in spin-to-charge conversion in Bi2Se3/NiFe heterostructure via interface engineering
Abstract
Topological insulators provide a promising platform for spintronic applications owing to their spin-momentum-locked surface states and efficient spin-to-charge conversion. Among these, Bi2Se3 has been the subject of intensive investigation due to its large bulk bandgap and single Dirac cone band structure. However, spin-to-charge conversion strongly depends on the quality of the topological insulator/ferromagnet interface. Here, we investigate spin transport and spin-to-charge conversion in sputter-deposited Bi2Se3/Ti/NiFe heterostructures at room temperature. The topological insulator layer is deposited on a CMOS-compatible silicon substrate. Low-temperature magnetoresistance measurements are conducted to establish the existence of a surface conducting channel in the deposited topological insulator layer. Pure spin current is injected into the Bi2Se3 layer through the titanium spacer layer via spin pumping induced by the spin precession in microwave-driven ferromagnetic resonance of the ferromagnetic film. Spin pumping studies are carried out by varying the thickness of the Bi2Se3 layer. The Bi2Se3 thickness dependence of the Gilbert damping reveals a pronounced 55% enhancement at a thickness of 4 nm, consistent with the hybridization of the top and bottom surface states of the topological insulator layer. The spin Hall angle, a parameter that quantifies the spin-to-charge conversion efficiency, exhibits an approximately one-order-of-magnitude enhancement upon insertion of the Ti spacer compared with Bi2Se3/NiFe heterostructures without the spacer. The significant enhancement of the spin Hall angle is attributed to Ti, which inhibits interdiffusion between the Bi2Se3 and NiFe layers, thereby protecting the topological surface states. Our findings highlight the role of titanium spacers in topological spintronics applications.
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BibTeX
@misc{maitra2026giant,
title = {{Giant enhancement in spin-to-charge conversion in Bi2Se3/NiFe heterostructure via interface engineering}},
author = {Sourav Rajat Subhra Maitra and Poulami Manna and Ravi Prakash Singh and Chandrasekhar Murapaka and Arabinda Haldar},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.01201},
eprint = {2606.01201},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.01201},
}
RIS
TY - UNPB
TI - Giant enhancement in spin-to-charge conversion in Bi2Se3/NiFe heterostructure via interface engineering
AU - Sourav Rajat Subhra Maitra
AU - Poulami Manna
AU - Ravi Prakash Singh
AU - Chandrasekhar Murapaka
AU - Arabinda Haldar
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2606.01201
UR - https://arxiv.org/abs/2606.01201
AB - Topological insulators provide a promising platform for spintronic applications owing to their spin-momentum-locked surface states and efficient spin-to-charge conversion. Among these, Bi2Se3 has been the subject of intensive investigation due to its large bulk bandgap and single Dirac cone band structure. However, spin-to-charge conversion strongly depends on the quality of the topological insulator/ferromagnet interface. Here, we investigate spin transport and spin-to-charge conversion in sputter-deposited Bi2Se3/Ti/NiFe heterostructures at room temperature. The topological insulator layer is deposited on a CMOS-compatible silicon substrate. Low-temperature magnetoresistance measurements are conducted to establish the existence of a surface conducting channel in the deposited topological insulator layer. Pure spin current is injected into the Bi2Se3 layer through the titanium spacer layer via spin pumping induced by the spin precession in microwave-driven ferromagnetic resonance of the ferromagnetic film. Spin pumping studies are carried out by varying the thickness of the Bi2Se3 layer. The Bi2Se3 thickness dependence of the Gilbert damping reveals a pronounced 55% enhancement at a thickness of 4 nm, consistent with the hybridization of the top and bottom surface states of the topological insulator layer. The spin Hall angle, a parameter that quantifies the spin-to-charge conversion efficiency, exhibits an approximately one-order-of-magnitude enhancement upon insertion of the Ti spacer compared with Bi2Se3/NiFe heterostructures without the spacer. The significant enhancement of the spin Hall angle is attributed to Ti, which inhibits interdiffusion between the Bi2Se3 and NiFe layers, thereby protecting the topological surface states. Our findings highlight the role of titanium spacers in topological spintronics applications.
ER -