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Incommensurate Spiral Spin Order in CaMn2Bi2 Observed via High-Pressure Neutron Diffraction
Madalynn Marshall1, Haozhe Wang2, Antonio M Dos Santos1
1Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
High-pressure neutron diffraction reveals that CaMn2Bi2 transitions to an incommensurate spiral spin order under extreme conditions. This emergent behavior is driven by the interaction between Mn magnetism and Bi spin-orbit coupling.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- CaMn2Bi2 exhibits antiferromagnetic ordering at ambient pressure.
- Understanding magnetic materials under extreme conditions is crucial for discovering novel quantum phenomena.
Purpose of the Study:
- To investigate the magnetic behavior of CaMn2Bi2 under high pressure.
- To elucidate the mechanisms driving magnetic transitions in this material.
Main Methods:
- High-pressure neutron diffraction.
- First-principles calculations with noncollinear spin orientation.
- Theoretical modeling of spin dynamics.
Main Results:
- High pressure induces an incommensurate spiral spin order in CaMn2Bi2, replacing the ambient pressure antiferromagnetic order.
- Sinusoidal spin order was observed up to 7.4 GPa.
- Strong hybridization between Mn d and Bi p orbitals leads to band crossing near the Fermi level.
- Competing antiferromagnetic order observed at different temperatures due to lattice frustration.
Conclusions:
- High pressure fundamentally alters the magnetic state of CaMn2Bi2.
- Spin-orbit coupling on Bi atoms plays a critical role in the high-pressure magnetic phase.
- The study provides a framework for exploring magnetic quantum materials using high-pressure neutron diffraction.
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