Pressure-correlation phase diagram unraveling quantum phase transitions in altermagnetic ε-FeOOH and…

Abstract

We establish a pressure-correlation phase diagram that yields multiple pressure-tunable quantum phase transitions in iron oxyhydroxide (ε-FeOOH) across three critical pressures, P_c1>P_c2>P_c3. The transitions arise from the competition among electron-correlation, crystal-field, and Hund's coupling. First-principles calculations reveal that the earlier reported high-spin (HS) to low-spin (LS) crossover at correlation-sensitive P_c1 is accompanied by a transition from charge-transfer to Mott insulating (CTI-MI) phase, and a change in the spin-quantization axis (SQA) from ŷ to x̂. The HS-LS crossover and CTI-MI transition is driven by the simultaneous increase in crystal-field splitting and decrease in Hund's coupling. The critical pressure P_c2 governing the structural transition from centrosymmetric Pnnm phase to noncentrosymmetric P2₁nm phase is found to be independent of electron-correlation. When correlation is strong, a third critical pressure (P_c3) emerges in the lower-pressure regime of the phase diagram. Validating the recent experimental observation, P_c3 is responsible for changing the SQA from ẑ to ŷ. By exhibiting altermagnetism in both P2₁nm and Pnnm phases and possessing finite anomalous Hall conductivity (AHC) only for SQA along x̂ and ŷ, ε-FeOOH enables a unique piezo-anomalous Hall effect where one can switch on the AHC at a lower pressure and change its direction at a higher pressure.

Anomalous Superfluid Response in Altermagnetic Superconductors
Christian Wiedemann, Danilo Nikolić, Matthias Eschrig +1
arXiv2 Sep 2026PreprintarXiv licenceFull textCondensed matterarXiv
Berry curvature quadrupole induced third-order anomalous Hall effect in altermagnetic KV₂Se₂O
Jiacheng Yao, Zhuocheng Lu, Zhichao Guo +1
arXiv30 Oct 2026PreprintarXiv licenceFull textCondensed matterarXiv
Phase Transitions in Disordered Altermagnetic Josephson Junctions
Chang-An Li
arXiv29 Sep 2026PreprintCC BY 4.0Full textCondensed matterarXiv
Anomalous temperature dependence in phase transitions via ballistic coalescence
Nalina Vadakkayil, Sutapa Roy, Jiarul Midya +1
arXiv31 Aug 2026PreprintCC BY 4.0Full textCondensed matterarXiv
Anomalous Structures of Fisher Zero Lines in Biorthogonal Dynamical Quantum Phase Transitions
Wen-Hui Nie, Chong Li, Lin-Cheng Wang
arXiv27 Oct 2026PreprintarXiv licenceFull textQuantum physics & quantum informationarXiv

Cite

BibTeX RIS

BibTeX

@misc{mandal2026pressurecorrelation,
  title = {{Pressure-correlation phase diagram unraveling quantum phase transitions in altermagnetic $ε$-FeOOH and realization of piezo-anomalous Hall effect}},
  author = {Arijit Mandal and Nayana Devaraj and Birabar Ranjit Kumar Nanda},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.03180},
  eprint = {2611.03180},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.03180},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Pressure-correlation phase diagram unraveling quantum phase transitions in altermagnetic ε-FeOOH and realization of piezo-anomalous Hall effect
AU  - Arijit Mandal
AU  - Nayana Devaraj
AU  - Birabar Ranjit Kumar Nanda
PY  - 2026
DA  - 2026/11/02
PB  - arXiv
DO  - 10.48550/arxiv.2611.03180
UR  - https://arxiv.org/abs/2611.03180
AB  - We establish a pressure-correlation phase diagram that yields multiple pressure-tunable quantum phase transitions in iron oxyhydroxide (ε-FeOOH) across three critical pressures, P_c1>P_c2>P_c3. The transitions arise from the competition among electron-correlation, crystal-field, and Hund's coupling. First-principles calculations reveal that the earlier reported high-spin (HS) to low-spin (LS) crossover at correlation-sensitive P_c1 is accompanied by a transition from charge-transfer to Mott insulating (CTI-MI) phase, and a change in the spin-quantization axis (SQA) from ŷ to x̂. The HS-LS crossover and CTI-MI transition is driven by the simultaneous increase in crystal-field splitting and decrease in Hund's coupling. The critical pressure P_c2 governing the structural transition from centrosymmetric Pnnm phase to noncentrosymmetric P2_1nm phase is found to be independent of electron-correlation. When correlation is strong, a third critical pressure (P_c3) emerges in the lower-pressure regime of the phase diagram. Validating the recent experimental observation, P_c3 is responsible for changing the SQA from ẑ to ŷ. By exhibiting altermagnetism in both P2_1nm and Pnnm phases and possessing finite anomalous Hall conductivity (AHC) only for SQA along x̂ and ŷ, ε-FeOOH enables a unique piezo-anomalous Hall effect where one can switch on the AHC at a lower pressure and change its direction at a higher pressure.
ER  -

Abstract

Related

Cite