Spin conservation protects the altermagnetic spin-splitter current from critical scattering
Abstract
Near a magnetic transition, critical fluctuations scatter electrons strongly, but the charge current survives, because long wavelength fluctuations barely turn the electron velocity. In an altermagnet the electric field also drives a spin current, the spin splitter effect, and a nearly forward scattering event that flips spin moves an electron to the other spin band at almost unchanged velocity. We show that the spin current shares the protection of the charge current only when the fluctuations conserve spin. Solving the Boltzmann equation with the full collision operator, including its change with the magnetic order, we find that forward flips equalize the two spin populations at equal energy at the quasiparticle rate, which in two dimensions grows linearly with the correlation length, whereas spin conserving fluctuations relax the spin current at a rate comparable to the charge relaxation rate. Fluctuations with the same resistivity can thus move the spin splitter ratio in opposite directions. Energy conservation protects the part of the spin current that follows the band shift of the occupied states, and the splitting blocks forward flips once the spin Fermi lines lie farther apart than the inverse correlation length. A disorder series at fixed reduced temperature measures the initial fall of the ratio with the magnetic resistivity independent of the order amplitude, and the growth of this slope toward the transition identifies spin flip critical fluctuations.
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BibTeX
@misc{jiang2026spin,
title = {{Spin conservation protects the altermagnetic spin-splitter current from critical scattering}},
author = {Yunxi Jiang and Hao Yu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41419},
eprint = {2610.41419},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41419},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Spin conservation protects the altermagnetic spin-splitter current from critical scattering
AU - Yunxi Jiang
AU - Hao Yu
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41419
UR - https://arxiv.org/abs/2610.41419
AB - Near a magnetic transition, critical fluctuations scatter electrons strongly, but the charge current survives, because long wavelength fluctuations barely turn the electron velocity. In an altermagnet the electric field also drives a spin current, the spin splitter effect, and a nearly forward scattering event that flips spin moves an electron to the other spin band at almost unchanged velocity. We show that the spin current shares the protection of the charge current only when the fluctuations conserve spin. Solving the Boltzmann equation with the full collision operator, including its change with the magnetic order, we find that forward flips equalize the two spin populations at equal energy at the quasiparticle rate, which in two dimensions grows linearly with the correlation length, whereas spin conserving fluctuations relax the spin current at a rate comparable to the charge relaxation rate. Fluctuations with the same resistivity can thus move the spin splitter ratio in opposite directions. Energy conservation protects the part of the spin current that follows the band shift of the occupied states, and the splitting blocks forward flips once the spin Fermi lines lie farther apart than the inverse correlation length. A disorder series at fixed reduced temperature measures the initial fall of the ratio with the magnetic resistivity independent of the order amplitude, and the growth of this slope toward the transition identifies spin flip critical fluctuations.
ER -