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Quantum Spin Torque Driven Transmutation of an Antiferromagnetic Mott Insulator
Marko D Petrović1, Priyanka Mondal1, Adrian E Feiguin2
1Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.
Physical Review Letters
|May 28, 2021
Summary
Quantum spin-transfer torque (STT) in antiferromagnetic Mott insulators requires a full quantum treatment. A spin-polarized current pulse induces a novel zigzag ferromagnetic phase in these materials.
Area of Science:
- Spintronics
- Quantum Magnetism
- Condensed Matter Physics
Background:
- Standard spin-transfer torque (STT) models treat localized spins classically, unsuitable for electron-correlated antiferromagnetic Mott insulators (AFMIs).
- AFMIs exhibit complex quantum ground states with entangled spin fluctuations, where classical models fail to initiate dynamics.
- A fully quantum approach is needed to describe spin angular momentum exchange in AFMIs.
Purpose of the Study:
- To investigate quantum spin-transfer torque (STT) in antiferromagnetic Mott insulators (AFMIs).
- To explore the induction of magnetic order in AFMIs via spin-polarized current injection.
- To understand the role of electron-electron repulsion and interlayer coupling in quantum STT.
Main Methods:
- Utilized a time-dependent density matrix renormalization group approach for quantum STT.
- Simulated the injection of a spin-polarized current pulse into a normal metal/AFMI bilayer.
- Investigated the effects of exchange interaction and interlayer hopping.
Main Results:
- Predicted the induction of a nonzero expectation value for localized spins in AFMIs.
- Identified a novel nonequilibrium phase: a spatially inhomogeneous ferromagnet with a zigzag spin profile.
- Demonstrated that spin absorption increases with electron-electron repulsion and without charge exchange.
Conclusions:
- The standard classical STT model is insufficient for AFMIs.
- Quantum STT can drive AFMIs into a unique zigzag ferromagnetic state.
- Electron-electron repulsion and charge-neutral interfaces enhance spin transfer in AFMIs.
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