Ultrafast Demagnetization Governed by Spin Fluctuations in CaRuO3/SrTiO3 Superlattice
Abstract
For ultrafast magnetization switching devices, critical slowing down in conventional ferromagnets near their Curie temperature constitutes a key challenge that must be overcome. In contrast to this typical behavior, we observe an anomalous acceleration of demagnetization in CaRuO3/SrTiO3 superlattices, a moderately correlated weak itinerant ferromagnet. The demagnetization rate increases with rising temperature, pump fluence, and applied magnetic field. To explain these anomalous phenomena, we develop a phenomenological model integrating the three-temperature model with self-consistent renormalization theory. Because the intrinsic gradient magnetism of the superlattice suppresses the typical divergence of specific heat, the conventional thermodynamic bottleneck is bypassed. Our model reveals that this decoupling enables the ultrafast dynamics to be predominantly governed by the spin-fluctuation-driven enhancement of the electron-spin scattering vertex. Our work demonstrates how spatial inhomogeneity can decouple macroscopic thermodynamic singularities from microscopic scattering processes, offering a new paradigm for manipulating ultrafast spin dynamics in correlated quantum materials. The pronounced sensitivity of the demagnetization rate to external parameters further suggests the potential for designing highly tunable ultrafast spintronic devices that leverage enhanced fluctuations near the magnetic instability.
Versions
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BibTeX
@misc{gao2026ultrafast,
title = {{Ultrafast Demagnetization Governed by Spin Fluctuations in CaRuO$_3$/SrTiO$_3$ Superlattice}},
author = {Yu-Han Gao and Wen-Xiao Shi and Yuan-Sha Chen and Ji-Rong Sun and Qing-Lin Yang and Xu Yang and Zhuo Deng and Peng-Tao Yang and Zheng Chang and Hong-Mei Feng and Wei He and Xiang-Qun Zhang and Zhao-Hua Cheng},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.02224},
eprint = {2607.02224},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.02224},
}
RIS
TY - UNPB
TI - Ultrafast Demagnetization Governed by Spin Fluctuations in CaRuO_3/SrTiO_3 Superlattice
AU - Yu-Han Gao
AU - Wen-Xiao Shi
AU - Yuan-Sha Chen
AU - Ji-Rong Sun
AU - Qing-Lin Yang
AU - Xu Yang
AU - Zhuo Deng
AU - Peng-Tao Yang
AU - Zheng Chang
AU - Hong-Mei Feng
AU - Wei He
AU - Xiang-Qun Zhang
AU - Zhao-Hua Cheng
PY - 2026
DA - 2026/07/02
PB - arXiv
DO - 10.48550/arxiv.2607.02224
UR - https://arxiv.org/abs/2607.02224
AB - For ultrafast magnetization switching devices, critical slowing down in conventional ferromagnets near their Curie temperature constitutes a key challenge that must be overcome. In contrast to this typical behavior, we observe an anomalous acceleration of demagnetization in CaRuO_3/SrTiO_3 superlattices, a moderately correlated weak itinerant ferromagnet. The demagnetization rate increases with rising temperature, pump fluence, and applied magnetic field. To explain these anomalous phenomena, we develop a phenomenological model integrating the three-temperature model with self-consistent renormalization theory. Because the intrinsic gradient magnetism of the superlattice suppresses the typical divergence of specific heat, the conventional thermodynamic bottleneck is bypassed. Our model reveals that this decoupling enables the ultrafast dynamics to be predominantly governed by the spin-fluctuation-driven enhancement of the electron-spin scattering vertex. Our work demonstrates how spatial inhomogeneity can decouple macroscopic thermodynamic singularities from microscopic scattering processes, offering a new paradigm for manipulating ultrafast spin dynamics in correlated quantum materials. The pronounced sensitivity of the demagnetization rate to external parameters further suggests the potential for designing highly tunable ultrafast spintronic devices that leverage enhanced fluctuations near the magnetic instability.
ER -