### Uittreksel

We develop a model for the magnonic contribution to the unidirectional spin Hall magnetoresistance (USMR) of heavy metal/ferromagnetic insulator bilayer films. We show that diffusive transport of Holstein-Primakoff magnons leads to an accumulation of spin near the bilayer interface, giving rise to a magnoresistance which is not invariant under inversion of the current direction. Unlike the electronic contribution described by Zhang and Vignale [Phys. Rev. B 94, 140411 (2016)2469-995010.1103/PhysRevB.94.140411], which requires an electrically conductive ferromagnet, the magnonic contribution can occur in ferromagnetic insulators such as yttrium iron garnet. We show that the magnonic USMR is, to leading order, cubic in the spin Hall angle of the heavy metal, as opposed to the linear relation found for the electronic contribution. We estimate that the maximal magnonic USMR in Pt|YIG bilayers is on the order of 10-8 but may reach values of up to 10-5 if the magnon gap is suppressed and can thus become comparable to the electronic contribution in, e.g., Pt|Co. We show that the magnonic USMR at a finite magnon gap may be enhanced by an order of magnitude if the magnon diffusion length is decreased to a specific optimal value that depends on various system parameters.

Taal | Engels |
---|---|

Artikelnummer | 064438 |

Aantal pagina's | 8 |

Tijdschrift | Physical Review B |

Volume | 99 |

Nummer van het tijdschrift | 6 |

DOI's | |

Status | Gepubliceerd - 28 feb 2019 |

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### Citeer dit

*Physical Review B*,

*99*(6), [064438]. DOI: 10.1103/PhysRevB.99.064438

}

*Physical Review B*, vol. 99, nr. 6, 064438. DOI: 10.1103/PhysRevB.99.064438

**Magnon contribution to unidirectional spin Hall magnetoresistance in ferromagnetic-insulator/heavy-metal bilayers.** / Sterk, W.P.; Peerlings, D.; Duine, R.A.

Onderzoeksoutput: Bijdrage aan tijdschrift › Tijdschriftartikel › Academic › peer review

TY - JOUR

T1 - Magnon contribution to unidirectional spin Hall magnetoresistance in ferromagnetic-insulator/heavy-metal bilayers

AU - Sterk,W.P.

AU - Peerlings,D.

AU - Duine,R.A.

PY - 2019/2/28

Y1 - 2019/2/28

N2 - We develop a model for the magnonic contribution to the unidirectional spin Hall magnetoresistance (USMR) of heavy metal/ferromagnetic insulator bilayer films. We show that diffusive transport of Holstein-Primakoff magnons leads to an accumulation of spin near the bilayer interface, giving rise to a magnoresistance which is not invariant under inversion of the current direction. Unlike the electronic contribution described by Zhang and Vignale [Phys. Rev. B 94, 140411 (2016)2469-995010.1103/PhysRevB.94.140411], which requires an electrically conductive ferromagnet, the magnonic contribution can occur in ferromagnetic insulators such as yttrium iron garnet. We show that the magnonic USMR is, to leading order, cubic in the spin Hall angle of the heavy metal, as opposed to the linear relation found for the electronic contribution. We estimate that the maximal magnonic USMR in Pt|YIG bilayers is on the order of 10-8 but may reach values of up to 10-5 if the magnon gap is suppressed and can thus become comparable to the electronic contribution in, e.g., Pt|Co. We show that the magnonic USMR at a finite magnon gap may be enhanced by an order of magnitude if the magnon diffusion length is decreased to a specific optimal value that depends on various system parameters.

AB - We develop a model for the magnonic contribution to the unidirectional spin Hall magnetoresistance (USMR) of heavy metal/ferromagnetic insulator bilayer films. We show that diffusive transport of Holstein-Primakoff magnons leads to an accumulation of spin near the bilayer interface, giving rise to a magnoresistance which is not invariant under inversion of the current direction. Unlike the electronic contribution described by Zhang and Vignale [Phys. Rev. B 94, 140411 (2016)2469-995010.1103/PhysRevB.94.140411], which requires an electrically conductive ferromagnet, the magnonic contribution can occur in ferromagnetic insulators such as yttrium iron garnet. We show that the magnonic USMR is, to leading order, cubic in the spin Hall angle of the heavy metal, as opposed to the linear relation found for the electronic contribution. We estimate that the maximal magnonic USMR in Pt|YIG bilayers is on the order of 10-8 but may reach values of up to 10-5 if the magnon gap is suppressed and can thus become comparable to the electronic contribution in, e.g., Pt|Co. We show that the magnonic USMR at a finite magnon gap may be enhanced by an order of magnitude if the magnon diffusion length is decreased to a specific optimal value that depends on various system parameters.

UR - http://www.scopus.com/inward/record.url?scp=85062520729&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.99.064438

DO - 10.1103/PhysRevB.99.064438

M3 - Article

VL - 99

JO - Physical Review B

T2 - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 6

M1 - 064438

ER -