Spintronics Meets Density Matrix Renormalization Group: Quantum Spin-Torque-Driven Nonclassical Magnetization Reversal and Dynamical Buildup of Long-Range Entanglement
| Author(s) | Petrović, Marko D. | |
| Author(s) | Mondal, Priyanka | |
| Author(s) | Feiguin, Adrian E. | |
| Author(s) | Plecháč, Petr | |
| Author(s) | Nikolić, Branislav K. | |
| Date Accessioned | 2022-01-24T15:17:32Z | |
| Date Available | 2022-01-24T15:17:32Z | |
| Publication Date | 2021-06-23 | |
| Description | This article was originally published in Physical Review X. The version of record is available at: https://doi.org/10.1103/PhysRevX.11.021062 | en_US |
| Abstract | We introduce the time-dependent density matrix renormalization group (tDMRG) as a solution to a long-standing problem in spintronics—how to describe spin-transfer torque (STT) between flowing spins of conduction electrons and localized spins within a magnetic material by treating the dynamics of both spin species fully quantum mechanically. In contrast to conventional Slonczewski-Berger STT, where the localized spins are viewed as classical vectors obeying the Landau-Lifshitz-Gilbert equation and where their STT-driven dynamics is initiated only when the spin polarization of flowing electrons and localized spins are noncollinear, quantum STT can occur when these vectors are collinear but antiparallel. Using tDMRG, we simulate the time evolution of a many-body quantum state of electrons and localized spins, where the former are injected as a spin-polarized current pulse while the latter comprise a quantum Heisenberg ferromagnetic metallic (FM) spin-1/2XXZ chain initially in the ground state with spin polarization antiparallel to that of injected electrons. The quantum STT reverses the direction of localized spins, but without rotation from the initial orientation, when the number of injected electrons exceeds the number of localized spins. Such nonclassical reversal, which is absent from Landau-Lifshitz-Gilbert dynamics, is strikingly inhomogeneous across the FM chain, and it can be accompanied by reduction of the magnetization associated with localized spins, even to zero at specific locations. This feature arises because quantum STT generates a highly entangled nonequilibrium many-body state of all flowing and localized spins, despite starting from the initially unentangled ground state of a mundane FM. Furthermore, the mutual information between localized spins at the FM edges remains nonzero even at infinite separation as the signature of dynamical buildup of long-range entanglement. The growth in time of entanglement entropy differentiates between the quantum and conventional (i.e., noncollinear) setups for STT, reaching a much larger asymptotic value in the former case. | en_US |
| Sponsor | We thank A. Suresh for technical help with TDNEGF+LLG-computed [16,23,24] movies in Supplemental Material [18] animating Fig. 1. M. D. P. and P. P. were supported by Army Research Office (ARO) MURI Award No. W911NF-14-0247. A. E. F. acknowledges support by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) Grant No. DE-SC0019275. P. M. and B. K. N. were supported by the U.S. National Science Foundation (NSF) under Grant No. ECCS 1922689. | en_US |
| Citation | Petrović Marko D, Priyanka Mondal, Adrian E Feiguin, Plecháč Petr, and Nikolić Branislav K. 2021. “Spintronics Meets Density Matrix Renormalization Group: Quantum Spin-Torque-Driven Nonclassical Magnetization Reversal and Dynamical Buildup of Long-Range Entanglement.” Physical Review X 11 (2). https://doi.org/10.1103/PhysRevX.11.021062. | en_US |
| ISSN | 2160-3308 | |
| URL | https://udspace.udel.edu/handle/19716/30093 | |
| Language | en_US | en_US |
| Publisher | Physical Review X | en_US |
| Keywords | Condensed Matter Physics | en_US |
| Keywords | Quantum Information | en_US |
| Keywords | Spintronics | en_US |
| Title | Spintronics Meets Density Matrix Renormalization Group: Quantum Spin-Torque-Driven Nonclassical Magnetization Reversal and Dynamical Buildup of Long-Range Entanglement | en_US |
| Type | Article | en_US |
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