High-Temperature ferromagnetism from site-selective filling in (Fe,Ni)6−δGeTe2
Abstract
The discovery of high-temperature ferromagnetism in the metallic van der Waals (vdW) system FeNGeTe2 has brought two-dimensional (2D) magnets into technologically relevant temperature scales. Specifically at N = 5, dilution of magnetic moments by nickel substitution counterintuitively achieves a record high Curie temperature of 478~K. Unraveling the origin of this nickel-substitution-induced enhancement is complicated by the compound's structural complexity, coexistent itinerant and local magnetic contributions, and mesoscopic compositional domains. Through coordinated structural and electronic characterization, we identify that the high-TC magnetic phase arises from a strain-stabilized Fe6GeTe2 nano-precipitate. Combining first-principles calculations and spin- and angle-resolved photoemission spectroscopy (ARPES), we uncover a site-specific electronic landscape in which interior iron atoms primarily host localized moments while the outer iron atoms neighboring the tellurium layers produce spin-polarized itinerant carriers that cross the vdW gap. The large energy cost associated with homogeneous nickel substitution is found to favor the spontaneous precipitation of the crystallographically and electronically ``clean'' high-TC phase. Finally, we compare metal-rich vdW magnets with binary magnetic alloys, and discuss the unifying roles of nano-precipitates in stabilizing otherwise unattainable bulk phases. Our work provides mechanistic insights into the record-high TC ferromagnetism in (Fe,Ni)5+δGeTe2, establishing a rigorous foundation for the atomic engineering of vdW magnetic metals informed by direct electronic signatures.
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BibTeX
@misc{werner2026hightemperature,
title = {{High-Temperature ferromagnetism from site-selective filling in (Fe,Ni)$_6-δ$GeTe$_2$}},
author = {Tyler L. Werner and Jonathan T. Reichanadter and Xiang Chen and Pranab K. Nag and Luna Y. Liu and Yu-Tsun Shao and Hongrui Zhang and Mingyang Guo and Wenxin Li and Zhibo Kang and Han Wu and Makoto Hashimoto and Donghui Lu and Turgut Yilmaz and Elio Vescovo and Sung-Kwan Mo and Barat Achinuq and Alexei Fedorov and Jacob C. Ruff and Ming Yi and Qiong Ma and David A. Muller and Eduardo H. da Silva Neto and Robert J. Birgeneau and Jeffrey B. Neaton and Yu He},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11862},
eprint = {2609.11862},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11862},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - High-Temperature ferromagnetism from site-selective filling in (Fe,Ni)_6−δGeTe_2
AU - Tyler L. Werner
AU - Jonathan T. Reichanadter
AU - Xiang Chen
AU - Pranab K. Nag
AU - Luna Y. Liu
AU - Yu-Tsun Shao
AU - Hongrui Zhang
AU - Mingyang Guo
AU - Wenxin Li
AU - Zhibo Kang
AU - Han Wu
AU - Makoto Hashimoto
AU - Donghui Lu
AU - Turgut Yilmaz
AU - Elio Vescovo
AU - Sung-Kwan Mo
AU - Barat Achinuq
AU - Alexei Fedorov
AU - Jacob C. Ruff
AU - Ming Yi
AU - Qiong Ma
AU - David A. Muller
AU - Eduardo H. da Silva Neto
AU - Robert J. Birgeneau
AU - Jeffrey B. Neaton
AU - Yu He
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11862
UR - https://arxiv.org/abs/2609.11862
AB - The discovery of high-temperature ferromagnetism in the metallic van der Waals (vdW) system Fe_NGeTe_2 has brought two-dimensional (2D) magnets into technologically relevant temperature scales. Specifically at N = 5, dilution of magnetic moments by nickel substitution counterintuitively achieves a record high Curie temperature of 478~K. Unraveling the origin of this nickel-substitution-induced enhancement is complicated by the compound's structural complexity, coexistent itinerant and local magnetic contributions, and mesoscopic compositional domains. Through coordinated structural and electronic characterization, we identify that the high-T_C magnetic phase arises from a strain-stabilized Fe_6GeTe_2 nano-precipitate. Combining first-principles calculations and spin- and angle-resolved photoemission spectroscopy (ARPES), we uncover a site-specific electronic landscape in which interior iron atoms primarily host localized moments while the outer iron atoms neighboring the tellurium layers produce spin-polarized itinerant carriers that cross the vdW gap. The large energy cost associated with homogeneous nickel substitution is found to favor the spontaneous precipitation of the crystallographically and electronically ``clean'' high-T_C phase. Finally, we compare metal-rich vdW magnets with binary magnetic alloys, and discuss the unifying roles of nano-precipitates in stabilizing otherwise unattainable bulk phases. Our work provides mechanistic insights into the record-high T_C ferromagnetism in (Fe,Ni)_5+δGeTe_2, establishing a rigorous foundation for the atomic engineering of vdW magnetic metals informed by direct electronic signatures.
ER -