2021年度 提案書 （Web公開用）

作成者： Justin LLANDRO （東北大学電気通信研究所/GP-Spin）

研究プロジェクト名： New and enhanced properties arising fromcurvature and topology in magnetic gyroids
概要： We propose to investigate the properties of nanoscale magnetic gyroid networks,(Figure 1A) which are predicted to exhibit enhanced properties and new effects throughthe interaction of their 3D curvature and topology with charge carriers and spin waves.
We aim to understand such emergent effects and then apply them to realize novel
spintronic devices.
コアメンバー： J. Llandro (Tohoku Univ.), M. Ohzeki (Tohoku Univ.), K. Yamamoto (JAEA), C.H.W. Barnes (Univ. Cambridge, UK), I. Gunkel, U. Steiner (AMI,Univ. Fribourg, Switzerland), N. Leo (CIC nanoGUNE, Spain), D. Karpov (ESRF, France), C. Donnelly (Univ. Cambridge, UK), A. Diaz, M. Holler, M. Guizar
Sicairos, J. Kohlbrecher, J. Gavilano, L. Heyderman (Paul Scherrer Institute, Switzerland), J. Dolan (Univ. Cambridge, UK), A. Kákay, J. Fassbender(Helmholtz Zentrum Dresden-Rossendorf, Germany)

We aim to employ substrate pre-patterning(directed self-assembly) to fully control theorientation of the gyroid’s chiral axes, which
we have so far achieved for the (111) gyroid
plane (chiral axis out of plane). Apart fromdefect-free gyroids, we will also investigate
gyroids containing half-integer topologicaldefects, following our X-ray nanotomographyobservations of such defects in gyroids(manuscript in preparation), so that we may
gain a comprehensive understanding ofmagnetotransport and spin-wave transmission
in gyroid nanostructures.

DSA pre-pattern for(111) gyroid plane

DSA patterned(111)-oriented gyroid

Gyroid (111) surface

100 nm59.6 60.2
60.2

60.2

60.2 59.6

1 µm

57.7
64.3

5864.35857.7

2018年度 報告書 （Web公開用）

作成者： Justin LLANDRO（東北大電気通信研究所）

研究プロジェクト名： New and enhanced properties arising fromcurvature and topology in magnetic gyroids
概要： Elucidated the 3D magnetization configuration of nanoscale magnetic gyroids(Figure 1A) by off-axis electron holography (Figure 1B) and finite-element
micromagnetic simulations (Figure 1C), for the purpose of evaluating gyroids as
meta-materials for spintronics and novel magnetic devices.
研究成果（実施状況）： Nanoscale NiFe
gyroids possess a ferromagnetic remanentstate with evidence of frustration,
displaying short-range order based oninteracting vertex pairs. These results
open possibilities for gyroids as
stochastic/neuromorphic computing
architectures and 3D magnonic crystals.
Analysis of polarized neutron scattering
data and X-ray tomographic imaging ofimproved Ni and Au gyroid samples iscurrently in progress.

AB

主要発表論文等：[1] J. Llandro et al., Advanced Materials, submitted (Mar 2019).

C2019年度 報告書 （Web公開用）

作成者： Justin LLANDRO（東北大電気通信研究所）

研究プロジェクト名： New and enhanced properties arising fromcurvature and topology in magnetic gyroids
概要： Ni75Fe25 nanoscale gyroids were fabricated (Figure 1A) and their 3D
magnetization configurations were elucidated by off-axis electron holography (Figure1B) and finite-element micromagnetic simulations (Figure 1C), for the purpose ofevaluating gyroids as meta-materials for fundamental and applied spintronics.
研究成果（実施状況）： Nanoscale Ni-Fe
gyroids were found to adopt an intricate
remanent state with no unique equilibrium
configuration, in which frustration causes somevertex pairs to adopt high-energy
magnetization states. The ability of the gyroid
to adopt high-entropy states is promising forreservoir computing applications (published).
Detailed analysis of bulk and interface
morphology of gyroids via 3D X-ray
nanotomography has been successfullycompleted, with highest-achieved resolution
for this technique (in preparation).

主要発表論文等： [1] J. Llandro et al., Nano Letters (2020).
DOI: 10.1021/acs.nanolett.0c00578

2020年度 報告書 （Web公開用） 作成者： Justin LLANDRO（東北大学電気通信研究所/GP-Spin）

研究プロジェクト名： New and enhanced properties arising fromcurvature and topology in magnetic gyroids
概要： After imaging the magnetization states of Ni75Fe25 nanoscale gyroids [1], we
investigated the morphology of gyroids via analysis of 3D X-ray nanotomography
data, SEM and AFM and how it may be controlled via substrate pre-patterning, inorder to enhance signatures of topological effects in magnetotransport.
研究成果（実施状況）：
Directed self-assembly via substrate prepatterning is effective in gyroids at eliminating
domain boundaries and improving ordering.
The next step, controlling chiral-axis
orientation, is in progress. Analysis of X-ray
nanotomography data revealed half-integer
topological defects in gyroids which combine
features of those observed in soft-mattersystems like liquid crystals and also of those incondensed matter (manuscript in preparation).

Gyroid (111)
surface

DSA (111)
pre-pattern

100 nmm = -1/2

2 µm

1 µm

unpatterned
gyroidDSA patterned
gyroid主要発表論文等： [1] J. Llandro et al., Nano Lett. 20, 3642 (2020).

m = +1/2

2021年度 報告書 （Web公開用）

作成者： Justin LLANDRO（東北大学電気通信研究所/GP‐Spin）

研究プロジェクト名： New and enhanced properties arising fromcurvature and topology in magnetic gyroids
概要： We aim to enhance signatures of topological effects on spin transport in magnetic
gyroids with well‐determined ordering and orientation. In single‐domain Ni gyroid films, weobserved strong angular dependence of the spin‐wave transport due to the interaction of theinhomogeneous gyroid magnetization revealed in our previous work [1] and induced eddy
currents localized in the gyroid branches.
研究成果（実施状況）：
We observed that in single‐domain Ni gyroid films ona coplanar waveguide that the FMR response isstrongly modified by the angle between the magnetic
field and the sample long axis. Between 40 and 120, a
second mode appears which exchanges energy withthe fundamental as a function of angle, and bothmodes display a non‐reciprocal component consistent
with the chiral nature of the gyroid. Ongoing
COMSOL simulations suggest that the microwave
field induces eddy currents localised in the gyroidbranches, which interact with the highly
inhomogeneous gyroid magnetization [1] morestrongly as the magnetic field angle matches the high‐symmetry directions of the gyroid network(manuscript in preparation).

主要発表論文等： [1] J. Llandro et al., Nano Lett. 20, 3642 (2020).