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The importance of the interface for picosecond spin pumping in antiferromagnet-heavy metal heterostructures

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Kholid, Farhan Nur 
Hamara, Dominik 
Hamdan, Ahmad Faisal Bin 
Nava Antonio, Guillermo 
Bowen, Richard 


jats:titleAbstract</jats:title>jats:pInterfaces in heavy metal (HM) - antiferromagnetic insulator (AFI) heterostructures have recently become highly investigated and debated systems in the effort to create spintronic devices that function at terahertz frequencies. Such heterostructures have great technological potential because AFIs can generate sub-picosecond spin currents which the HMs can convert into charge signals. In this work we demonstrate an optically induced picosecond spin transfer at the interface between AFIs and Pt using time-domain THz emission spectroscopy. We select two antiferromagnets in the same family of fluoride cubic perovskites, KCoFjats:sub3</jats:sub> and KNiFjats:sub3</jats:sub>, whose magnon frequencies at the centre of the Brillouin zone differ by an order of magnitude. By studying their behaviour with temperature, we correlate changes in the spin transfer efficiency across the interface to the opening of a gap in the magnon density of states below the Néel temperature. Our observations are reproduced in a model based on the spin exchange between the localized electrons in the antiferromagnet and the free electrons in Pt. Through this comparative study of selected materials, we are able to shine light on the microscopy of spin transfer at picosecond timescales between antiferromagnets and heavy metals and identify a key figure of merit for its efficiency: the magnon gap. Our results are important for progressing in the fundamental understanding of the highly discussed physics of the HM/AFI interfaces, which is the necessary cornerstone for the designing of femtosecond antiferromagnetic spintronics devices with optimized characteristics.</jats:p>


Funder: Royal Society


Article, /639/766/119/1001, /639/766/119/997, /639/766/119/544, /639/766/400/561, /639/766/400/584, /140/125, article

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Nature Communications

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Springer Science and Business Media LLC
EC | Horizon 2020 Framework Programme (EU Framework Programme for Research and Innovation H2020) (861300)
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