Pressure-Induced Metal-Insulator and Paramagnet-Altermagnet Transitions in Rutile OsO2 Single Crystals
arXiv:2603.07008 · doi:10.1016/j.newton.2026.100441
Abstract
Altermagnets with compensated spin structures and nonrelativistic spin splitting have emerged as a new class of magnetic materials. Rutile OsO2 has been theoretically predicted to be altermagnetic, but experimental studies have been limited by synthesis challenges. We have succeeded in synthesizing high-quality single crystals of rutile OsO2. Electrical transport studies reveal that OsO2 is highly conductive and exhibits clear Fermi liquid behavior, indicating strong electron-electron scattering. Magnetic measurements show that the crystals are isotropically paramagnetic. Density-functional theory calculations indicate that bulk OsO2 is semimetallic with coexisting electron and hole pockets, with its magnetic ground state strongly dependent on the on-site Coulomb correlation U. Angle-resolved photoemission spectroscopy studies unveil that the bulk bands do not yet show altermagnetic spin splitting. Interestingly, resistivity is rather pressure sensitive: at 44 GPa, a clear metal-insulator transition occurs. Hybrid functional calculations reveal that applying pressure significantly increases the Hubbard U value, driving a phase transition from a paramagnetic metal to an altermagnetic metal, and eventually to an altermagnetic insulator. These findings suggest that tuning external pressure effectively modulates the magnetic ground state of OsO2, providing a pathway to realize altermagnetism in this material.
20 pages, 7 figures, published at Newton
References in corpus (27)
- WannierTools: An open-source software package for novel topological materials
- Maximally-localized Wannier functions for entangled energy bands
- Fermi-liquid instabilities at magnetic quantum phase transitions
- Crystal Hall effect in Collinear Antiferromagnets
- Superconductivity near 80 Kelvin in single crystals of La3Ni2O7 under pressure
- Observation of the Anomalous Hall Effect in a Collinear Antiferromagnet
- Observation of spin splitting torque in a collinear antiferromagnet RuO2
- Tilted spin current generated by the collinear antiferromagnet RuO2
- Observation of spin-splitter torque in collinear antiferromagnetic RuO
- Itinerant Antiferromagnetism in RuO
- Anomalous Antiferromagnetism in Metallic RuO Determined by Resonant X-ray Scattering
- A Piezoelectric, Strain-Controlled Antiferromagnetic Memory Insensitive to Magnetic Fields
- Nonmagnetic Ground State in RuO Revealed by Muon Spin Rotation
- Absence of altermagnetic spin splitting character in rutile oxide RuO
- Carrier freeze-out induced metal-insulator transition in oxygen deficient SrTiO3 films
- Saturation of the anomalous Hall effect at high magnetic fields in altermagnetic RuO2
- Integration of the Noncollinear Antiferromagnetic Metal Mn3Sn onto Ferroelectric Oxides for Electric-Field Control
- Linear magnetoresistance in the low-field limit in density-wave materials
- Giant Piezospintronic Effect in a Noncollinear Antiferromagnetic Metal
- Fermi-liquid behavior of non-altermagnetic RuO
- Magnetic-field induced resistivity minimum with in-plane linear magnetoresistance of the Fermi liquid in SrTiO3-x single crystals
- Crystal structure and absence of magnetic order in single crystalline RuO
- Multiband transport in RuO
- A two-dimensional electron gas based on a 5s oxide with high room-temperature mobility and strain sensitivity
- Universal Scaling Behavior of Transport Properties in Non-Magnetic RuO
- Nature of electrons from oxygen vacancies and polar catastrophe at LaAlO3/SrTiO3 interfaces
- Spin-degenerate bulk bands and topological surface states associated with Dirac nodal lines in RuO2