Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO2

Federico Mazzola; Chi-Ming Yim; Veronika Sunko; Seunghyun Khim; Pallavi Kushwaha; Oliver J. Clark; Lewis Bawden; Igor Marković; Dibyashree Chakraborti; Timur K. Kim; Moritz Hoesch; Andrew P. Mackenzie; Peter Wahl; Philip D. C. King

doi:10.1038/s41535-022-00428-8

Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO₂

Federico Mazzola^*
, Chi-Ming Yim
, Veronika Sunko
, Seunghyun Khim
, Pallavi Kushwaha
, Oliver J. Clark
, Lewis Bawden
, Igor Marković
, Dibyashree Chakraborti
, Timur K. Kim
, Moritz Hoesch
, Andrew P. Mackenzie
, Peter Wahl
, Philip D. C. King^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Controlling spin wave excitations in magnetic materials underpins the burgeoning field of magnonics. Yet, little is known about how magnons interact with the conduction electrons of itinerant magnets, or how this interplay can be controlled. Via a surface-sensitive spectroscopic approach, we demonstrate a strong and highly-tuneable electron-magnon coupling at the Pd-terminated surface of the delafossite oxide PdCoO₂, where a polar surface charge mediates a Stoner transition to itinerant surface ferromagnetism. We show how the coupling can be enhanced 7-fold with increasing surface disorder, and concomitant charge carrier doping, becoming sufficiently strong to drive the system into a polaronic regime, accompanied by a significant quasiparticle mass enhancement. Our study thus sheds new light on electron-magnon interactions in solid-state materials, and the ways in which these can be controlled.

Original language	English
Article number	20
Number of pages	6
Journal	npj Quantum Materials
Volume	7
DOIs	https://doi.org/10.1038/s41535-022-00428-8
Publication status	Published - 11 Feb 2022

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RS Phil King: Electronic Structure Engineering of Novel Topological Phases
King, P. (PI)
1/10/18 → 30/09/21
Project: Fellowship
STEM - Strain-tuning of Emergent: Strain-Tuning of Emergent states of Matter
Wahl, P. (PI) & Rost, A. (CoI)
EPSRC
1/08/18 → 31/07/21
Project: Standard
ERC Starting Grant QUESTDO: H2020 ERC Starting Grant QUESTDO
King, P. (PI)
European Research Council
1/01/17 → 31/12/21
Project: Fellowship

Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO2 (dataset)
Mazzola, F. (Creator), Yim, C. M. (Creator), Sunko, V. (Creator), Khim, S. (Creator), Kushwaha, P. (Creator), Clark, O. J. (Creator), Bawden, L. (Creator), Markovic, I. (Creator), Chakraborti, D. (Creator), Kim, T. (Creator), Hoesch, M. (Creator), Mackenzie, A. (Creator), Wahl, P. (Creator) & King, P. (Creator), University of St Andrews, 15 Feb 2022
DOI: 10.17630/1914b7df-3421-422a-8697-774a149c7f00
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Cite this

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title = "Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO2",

abstract = "Controlling spin wave excitations in magnetic materials underpins the burgeoning field of magnonics. Yet, little is known about how magnons interact with the conduction electrons of itinerant magnets, or how this interplay can be controlled. Via a surface-sensitive spectroscopic approach, we demonstrate a strong and highly-tuneable electron-magnon coupling at the Pd-terminated surface of the delafossite oxide PdCoO2, where a polar surface charge mediates a Stoner transition to itinerant surface ferromagnetism. We show how the coupling can be enhanced 7-fold with increasing surface disorder, and concomitant charge carrier doping, becoming sufficiently strong to drive the system into a polaronic regime, accompanied by a significant quasiparticle mass enhancement. Our study thus sheds new light on electron-magnon interactions in solid-state materials, and the ways in which these can be controlled. ",

author = "Federico Mazzola and Chi-Ming Yim and Veronika Sunko and Seunghyun Khim and Pallavi Kushwaha and Clark, \{Oliver J.\} and Lewis Bawden and Igor Markovi{\'c} and Dibyashree Chakraborti and Kim, \{Timur K.\} and Moritz Hoesch and Mackenzie, \{Andrew P.\} and Peter Wahl and King, \{Philip D. C.\}",

note = "Funding: We gratefully acknowledge support from the European Research Council (through the QUESTDO project, 714193), the Royal Society, the Max Planck Society, and the UKRI Engineering and Physical Sciences Research Council (Grant No. EP/S005005/1). V.S., O.J.C., and L.B. acknowledge the EPSRC for PhD studentship support through Grants EP/L015110/1, EP/K503162/1, and EP/G03673X/1, respectively. I.M. and D.C. acknowledge studentship support from the International Max-Planck Research School for Chemistry and Physics of Quantum Materials.",

year = "2022",

month = feb,

day = "11",

doi = "10.1038/s41535-022-00428-8",

language = "English",

volume = "7",

journal = "npj Quantum Materials",

issn = "2397-4648",

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TY - JOUR

T1 - Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO2

AU - Mazzola, Federico

AU - Yim, Chi-Ming

AU - Sunko, Veronika

AU - Khim, Seunghyun

AU - Kushwaha, Pallavi

AU - Clark, Oliver J.

AU - Bawden, Lewis

AU - Marković, Igor

AU - Chakraborti, Dibyashree

AU - Kim, Timur K.

AU - Hoesch, Moritz

AU - Mackenzie, Andrew P.

AU - Wahl, Peter

AU - King, Philip D. C.

N1 - Funding: We gratefully acknowledge support from the European Research Council (through the QUESTDO project, 714193), the Royal Society, the Max Planck Society, and the UKRI Engineering and Physical Sciences Research Council (Grant No. EP/S005005/1). V.S., O.J.C., and L.B. acknowledge the EPSRC for PhD studentship support through Grants EP/L015110/1, EP/K503162/1, and EP/G03673X/1, respectively. I.M. and D.C. acknowledge studentship support from the International Max-Planck Research School for Chemistry and Physics of Quantum Materials.

PY - 2022/2/11

Y1 - 2022/2/11

N2 - Controlling spin wave excitations in magnetic materials underpins the burgeoning field of magnonics. Yet, little is known about how magnons interact with the conduction electrons of itinerant magnets, or how this interplay can be controlled. Via a surface-sensitive spectroscopic approach, we demonstrate a strong and highly-tuneable electron-magnon coupling at the Pd-terminated surface of the delafossite oxide PdCoO2, where a polar surface charge mediates a Stoner transition to itinerant surface ferromagnetism. We show how the coupling can be enhanced 7-fold with increasing surface disorder, and concomitant charge carrier doping, becoming sufficiently strong to drive the system into a polaronic regime, accompanied by a significant quasiparticle mass enhancement. Our study thus sheds new light on electron-magnon interactions in solid-state materials, and the ways in which these can be controlled.

AB - Controlling spin wave excitations in magnetic materials underpins the burgeoning field of magnonics. Yet, little is known about how magnons interact with the conduction electrons of itinerant magnets, or how this interplay can be controlled. Via a surface-sensitive spectroscopic approach, we demonstrate a strong and highly-tuneable electron-magnon coupling at the Pd-terminated surface of the delafossite oxide PdCoO2, where a polar surface charge mediates a Stoner transition to itinerant surface ferromagnetism. We show how the coupling can be enhanced 7-fold with increasing surface disorder, and concomitant charge carrier doping, becoming sufficiently strong to drive the system into a polaronic regime, accompanied by a significant quasiparticle mass enhancement. Our study thus sheds new light on electron-magnon interactions in solid-state materials, and the ways in which these can be controlled.

U2 - 10.1038/s41535-022-00428-8

DO - 10.1038/s41535-022-00428-8

M3 - Article

SN - 2397-4648

VL - 7

JO - npj Quantum Materials

JF - npj Quantum Materials

M1 - 20

ER -

Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO2

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RS Phil King: Electronic Structure Engineering of Novel Topological Phases

STEM - Strain-tuning of Emergent: Strain-Tuning of Emergent states of Matter

ERC Starting Grant QUESTDO: H2020 ERC Starting Grant QUESTDO

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Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO2 (dataset)

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Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO₂