United States

Current-induced magnetization switching via spin-orbit torque (SOT) has been intensively investigated for conventional memory applications. With the emergence of multi-states devices that can be utilized in both memory and computing operations, research has pivoted to focus on all electrical-induced multiple resistant states to provide complementary hardware for unconventional computing [1]. SOT-based multi-state devices can mimic artificial synapses and neurons for unconventional computing due to their non-volatility, high scalability, and low power consumption. Artificial synapses are utilized for memory function, acting as junctions between pre-and post-neurons, these continuously being adjusted to tune the strength between two neurons. Artificial neurons integrate all the input stimuli and fire once the accumulated potential reaches a certain threshold. SOT manipulation of multiple magnetization states can be realized by controlling domain wall propagation and modulating domain wall nucleation to emulate synapses [2]. Domain wall propagation requires controllable pinning while domain nucleation can be effectively achieved by modifying the magnetic anisotropy energy. In this work, SOT-induced domain wall nucleation in Pt/Co system is demonstrated by engineering its interface to lower the anisotropy energy. A low magnetic anisotropy energy of 1.35×105 J/m3 has been achieved in Pt (5 nm)/Co (1.2 nm)/HfOx (2 nm)/Ti (2 nm) structure, as obtained from the hysteresis loops shown in Fig. 1(a) and (b). Electrical and Kerr microscopy measurements were carried out to determine the multiple resistance states. Figure 2(a) shows the Hall resistance Rxy change with magnetic field HOOP. Figure 2(b) shows the pulse current-induced multiple resistance; the insets show the domain images after sending a pulse current (I) from 6 to 9 mA. The results clearly indicate the multi-states in Pt/Co/HfOx/Ti system are driven by current, which is promising for synaptic memory-driven neuromorphic applications.&lt;br&gt;&lt;br&gt;
**References** [1] Zhou, J., et. al., Adv. Mater. 33, 2103672 (2021).
[2] Jin, T., et. al., J. Phys. D: Appl. Phys, 52, 445001 (2019).&lt;br&gt;&lt;br&gt;

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MMM 2022

All electrical Manipulation of Multiple Resistant States via Modifying Magnetic Anisotropy for Emulating Synaptic Memory

Current-induced magnetization switching via spin-orbit torque (SOT) has been intensively investigated for conventional memory applications. With the emergence of multi-states devices that can be utilized in both memory and computing operations, research has pivoted to focus on all electrical-induced multiple resistant states to provide complementary hardware for unconventional computing [1]. SOT-based multi-state devices can mimic artificial synapses and neurons for unconventional computing due to their non-volatility, high scalability, and low power consumption. Artificial synapses are utilized for memory function, acting as junctions between pre-and post-neurons, these continuously being adjusted to tune the strength between two neurons. Artificial neurons integrate all the input stimuli and fire once the accumulated potential reaches a certain threshold. SOT manipulation of multiple magnetization states can be realized by controlling domain wall propagation and modulating domain wall nucleation to emulate synapses [2]. Domain wall propagation requires controllable pinning while domain nucleation can be effectively achieved by modifying the magnetic anisotropy energy. In this work, SOT-induced domain wall nucleation in Pt/Co system is demonstrated by engineering its interface to lower the anisotropy energy. A low magnetic anisotropy energy of 1.35×105 J/m3 has been achieved in Pt (5 nm)/Co (1.2 nm)/HfOx (2 nm)/Ti (2 nm) structure, as obtained from the hysteresis loops shown in Fig. 1(a) and (b). Electrical and Kerr microscopy measurements were carried out to determine the multiple resistance states. Figure 2(a) shows the Hall resistance Rxy change with magnetic field HOOP. Figure 2(b) shows the pulse current-induced multiple resistance; the insets show the domain images after sending a pulse current (I) from 6 to 9 mA. The results clearly indicate the multi-states in Pt/Co/HfOx/Ti system are driven by current, which is promising for synaptic memory-driven neuromorphic applications. 
**References** [1] Zhou, J., et. al., Adv. Mater. 33, 2103672 (2021).
[2] Jin, T., et. al., J. Phys. D: Appl. Phys, 52, 445001 (2019). 

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technical paper

#### Welcome to the 67th Annual Conference on Magnetism and Magnetic Materials, MMM 2022!

The Conference was held from October 31 to November 4 and offers both in-person and on-demand content.

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Magnetic skyrmions are “topologically protected” solitons, that have recently received increased attention due to their potential application as information carriers and for unconventional computing [1]. While the current-driven dynamics has been explored deeply, the theory of temperature gradient-induced dynamics - Skyrmion-Caloritronics [2] - is still at its early stages of development but it is particularly promising due to its low energy consumption.
In this work, we study the effects of thermal gradients on skyrmion motion in different systems (single-layer FM with interfacial Dzyaloshinskii-Moriya interaction (IDMI), multilayer, and synthetic antiferromagnets (SAFs)) inspired by the experimental results of Ref. [2] and from a fundamental point of view. We observe that, when driven by the entropic torque, skyrmions in single layers move from the cold to the hot region with a finite skyrmion Hall angle (Fig. 1), while in multilayers they move in the opposite direction (from hot to cold region) (Fig. 2). The latter is in qualitative agreement with the experimental observations (Fig. 3a in Ref. [2]). We demonstrate that this difference is due to the distinct scaling relations characterizing the two systems, and to the existence of a magnetostatic field gradient linked to the variation of saturation magnetization (MS) which cannot be neglected in magnetic multilayers. The numerical results are corroborated by a generalized Thiele’s equation developed for this scenario. Moreover, we show that the skyrmion Hall angle is completely suppressed in SAFs, similarly to the current-driven skyrmions [3,4].
Our results have fundamental implications in the future development of skyrmionic devices combining thermal gradients and SOTs where the proper temperature dependence of the parameters should be taken into account.
See Ref. [5] for founding statement. 
**References** [1] J. Zázvorka, et al., Nat. Nanotechnol. 14, 658 (2019).

[2] Z. Wang, et al., Nat. Electron. 3, 672 (2020).

[3] X. Zhang, et al., Nat. Commun. 7, 10293 (2016).

[4] R. Tomasello, et al., J. Phys. D. Appl. Phys. 50, 325302 (2017).

[5] This work was supported by the Project No. PRIN 2020LWPKH7 funded by the Italian Ministry of University and Research, and by the PETASPIN association (www.petaspin.com). JB acknowledges support from the Royal Society through a University Research Fellowship. E.R. acknowledges the economical support of the COST Action CA 17123 (MAGNETOFON) within the STSM program. We would like to acknowledge networking support from COST Action No. CA17123 “Ultrafast opto magneto electronics for nondissipative information technology.”

[6] W. Li, et al., Adv. Mater. 31, 1807683 (2019). 

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Skyrmion Caloritronics: a promising Strategy to manipulate Skyrmions

Magnetic topological textures could serve as powerful tools in the development of next-generation spintronics devices, especially in terms of stability and energy consumption. Two-dimensional (2D) magnetic solitons such as chiral domain walls or skyrmions were mostly under focus for the last decade. Beyond these 2D textures, a new interest has risen for more complex quasi-particles that display variations over the thickness, i.e., three-dimensional (3D) objects. Examples include different skyrmion phases [1], bobbers [2] or even hopfions [3]. In this work, we show how by engineering Pt/Co/Al based multilayers with variable Co thickness, we observe the signature of new textures, called skyrmionic cocoons [4] that are only present in a fraction of the magnetic layers. Interestingly, these cocoons can coexist with more standard ‘tubular’ skyrmions going through all the multilayer as evidenced by the existence of two very different contrasts in the magnetic force microscopy (MFM) images recorded at room temperature (Fig. 1a). Moreover, the field dependence of skyrmionic cocoons has also been studied with Fourier transform holography measurements (FTH) with similar observations (Fig. 1b). FTH additionally puts forward various magnetic phase transitions as well as the existence of an attractive interaction between cocoons. The presence of these novel skyrmionic textures has also been investigated by micromagnetic simulations (Fig. 1c). The relaxed states can easily be identified with the different experimental contrasts: the columnar skyrmion tubes (resp. cocoons) corresponds to the strong contrast (resp. weak contrast). Thus, this coexistence of various magnetic textures in multilayers and the discovery of a novel magnetic texture are particularly interesting as they can open new paths for three-dimensional spintronics. 
**References** [1] A.O. Mandru et al. Nature communications 11,1 (2020)
[2] F. Zheng et al. Nature Nanotechnology 13, 451 (2018)
[3] N. Kent et al. Nature communications 12, 1 (2021)
[4] M. Grelier et al. arXiv: 2205.01172 (2022). 
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Skyrmionic 3D cocoons in magnetic multilayers

Spin based photovoltaic (PV) effect is novel research in energy harvesting area.Recently, spin-PV effect was demonstrated on magnetic tunnel junction-based molecular spintronics (MTJMSD).This prior work mainly focused on NiFe/AlOx/NiFe MTJ[1].To advance this field there is a critical need of investigating a wide range of magnetic materials.MgO insulator and CoFeB electrode-based MTJS are well established for showing high TMR ratio and heavily studied for computer memory operation.However,they have never been integrated into the molecular spintronics study.This study made effort to develop a fabrication method by which CoFeB/MgO/CoFeB MTJ could be produced in the cross-junction form to facilitate transport and electrical measurements.To do so we had to overcome numerous fabrication challenges.First, we investigated the air stability of CoFeB using reflectance study as a function of temperature.We observed that CoFeB was stable in air up to ~100C.To produce stable and low leakage current tunnel junctions we iteratively investigated the role of multiple bottom electrode fabrication factors through Taguchi Design of experiment.We produced bottom electrode in such a way that thin films have optimum tapered edge geometry and ~0.15 nm Rq roughness.To produce exposed side edges for molecule spin channel attachment we deposited MgO and top electrode through photolithorgraphically produced cavity perpendicular to the bottom electrode. To convert MTJ into MTJMSD we electrochemically bridged the SMM molecules across MgO and conducted current-voltage study before and after molecule spin channel creation.Interestingly, SMM produced current suppression at room temperature by ~200% at 300mV. Also, we observed PV effect. This MTJ produced 0.08 open circuit voltage and 5.19E-9 saturation current under 1sun(1000 mW/cm2) light intensity. To investigate the mechanism, we perform KPAFM. The difference between electrodes before and after SMM bridging was 33 and 150 mV, respectively. Higher difference in KPAFM voltage signifies a large difference in electrode resistivity. KPAFM also suggests the observed PV effect is mainly from the impacted ferromagnetic electrode region and not due to the interaction of light at molecular channels. 
**References** 1- P. Tyagi and C. Riso, "Molecular spintronics devices exhibiting properties of a solar cell," Nanotechnology, vol. 30, p. 495401, 2019/09/19 2019.
2- P. Tyagi and C. Riso, "Magnetic force microscopy revealing long range molecule impact on magnetic tunnel junction based molecular spintronics devices," Organic Electronics, vol. 75, p. 105421, 2019/12/01/ 2019.
3-Heersche, H. B., De Groot, Z., Folk, J. A., Van Der Zant, H. S. J., Romeike, C., Wegewijs, M. R., ... & Cornia, A. (2006). Electron transport through single Mn 12 molecular magnets. Physical review letters, 96(20), 206801.
4- Jo MH, Grose JE, Baheti K, Deshmukh MM, Sokol JJ, Rumberger EM, Hendrickson DN, Long JR, Park H, Ralph DC. Signatures of molecular magnetism in single-molecule transport spectroscopy. Nano Lett. 2006 Sep;6(9):2014-20. doi: 10.1021/nl061212i. PMID: 16968018.
5- Bogani, L., Wernsdorfer, W. Molecular spintronics using single-molecule magnets. Nature Mater 7, 179–186 (2008). https://doi.org/10.1038/nmat2133 
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Single Molecular Magnet (SMM) Producing Photovoltaic Effect(PV) on Magnetic Tunnel Junction

Magnetometers are used for navigation, the detection of submarines and underwater debris, archaeological and geological surveys, as well as in the exploration of our solar system and even in our mobile devices [1-2]. Recently, designs of solid-state quantum magnetometers have stimulated particular interest both for their small size [3], and for their potential to operate without any optical components or applied microwave fields [4].
In this work we model Optically/Electrically Detected Magnetic Resonance (ODMR/EDMR) of the Silicon vacancy in Silicon Carbide, a budding candidate for solid-state quantum magnetometry, using quantum master equations. The Silicon vacancy can be thought of as a S = 3/2 synthetic atom, and its spin states are sensitive to magnetic fields via the Zeeman effect. In ODMR, magnetic resonances of the Zeeman field are detected by extrema in the normalized photoluminescence signal when a transverse microwave field is applied. In EDMR, magnetic resonances of the Zeeman field are detected by extrema in the normalized current, generated when a conduction electron couples to the vacancy’s spin and is allowed to recombine with a valence hole in a spin-dependent manner. In both cases, the photoluminescence/current is calculated from the steady-state density matrix populations and compared to recent experimental results [5-7].
We acknowledge support from NSF DMR-1921877. 
**References** [1] Budker, D., Romalis, M., Nature Phys 3, 227–234 (2007)
[2] Ness, N.F., Space Sci Rev 11, 459–554 (1970)
[3] Kraus, H., Soltamov, V., Fuchs, F. et al., Sci Rep 4, 5303 (2014)
[4] Cochrane, C., Blacksberg, J., Anders, M. et al., Sci Rep 6, 37077 (2016)
[5] Kraus, H., Soltamov, V., Riedel, D. et al., Nature Phys 10, 157–162 (2014)
[6] Fischer, M., Sperlich, A., Kraus, H. et al., Phys. Rev. Applied 9, 054006 (2018)
[7] Cochrane, C., Kraus, H., Neudeck, P. et al., MSF 924 988-992 (2018)

Theory of a Single Si Vacancy in SiC as a Quantum Sensor of Magnetic Fields

Spintronic devices operating on spin waves (SW) can be more efficient than oxide semiconductors due to their high frequencies and low energy cost. Therefore, SW based technology may prove to be more powerful than CMOS devices due to its intrinsic characteristics [1]. Magnetic field is the primary stimuli controlling magnetism and SW dynamics. Thus, the study of the influence of the magnetic field on ferromagnetic nanostructures with different geometries is critical for modern technologies, especially for the development of 3D-magnonic circuits, where the geometric constraints generate a strong relationship between the fields of demagnetization, exchange and bias.
Recently, it has been experimentally demonstrated that the 3D network formed from the crescent-shape nanorods (CSN) is promising for development of 3D ferromagnetic systems for various applications [2]. As yet, CSN-s have not been investigated for their effect on SW spectra and manipulations in relation to magnitude and magnetic field orientation. Untypical results make our analysis relevant for future investigations and applications. In particular, we show that there are edge localized and bulk SW modes. The edge modes decouple when the external magnetic field rotates, Fig. 1. Thus, the two edges of the CSN behave as two distinct channels for SW guiding, whose frequency can be controlled by the magnetic field magnitude and orientation. Interestingly, both the polar and azimuthal rotations of the field significantly affect the ferromagnetic resonance spectra. It alters the number of most intense lines in the spectra and their frequency range. When additional magnetic layer is added to the CSN, the magnetostatic coupling between the elements leads to additional modes splitting, Fig. 2. Thus, the CSN-s can support 3D magnonic circuits at nanoscale, which operate at wide range of frequencies, offer multimode operation, and promise nonreciprocal effects. 
The research has received founding from the NCN Poland, project no 2020/39/I/ST3/02413.
**References** [1] A. V. Chumak et al., Advances in Magnetics Roadmap on Spin-Wave Computing, IEEE Trans. Magn. 58, 1 (2022).
[2] A. May, et al., Realisation of a frustrated 3D magnetic nanowire lattice. Commun. Phys. 2, 13 (2019). 

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Control of the spin wave spectra by magnetic field orientation and magnitude in crescent

We demonstrate field-free spin–orbit torque (SOT) switching in a perpendicular CoFeB/Ta/CoFeB tri-layer device through manipulation of inter-layer exchange coupling.
This finding is based on experimental and simulation results. In the Ta thickness range of 0.5~3 nm, the device exhibited a clear Ruderman–Kittel–Kasuya–Yosida (RKKY) oscillation
where the anisotropy can be modulated. This resulted in a tilted magnetic moment and thus created a tunable SOT switching window. We found that the SOT switching current density (Jc)also appeared to vary with the Ta thickness (tTa). By cross-tuning the anisotropy and Jc with Ta spacer thickness, field-free SOT can be enabled in this tri-layer system. With microspin
simulation we show that, when the out-of-plane spin polarization from the pinned layer generated a torque that broke the symmetry of the free layer, precession could be enabled along the
x-y plane. This made it possible to achieve perpendicular magnetization switching without an external magnetic field by overcoming the damping torque. Through simulations we also
confirm that the Neel orange peel effect became non-negligible due to interface roughness and coupling effect in the presence of perpendicular anisotropy. Fortunately, the Neel field
induced by the Neel orange peel effect was found to favor the zero-field reversal.

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Fig.1 (a) Schematic illustration of the Ta/MgO(1)/CoFeB(1.2)/Ta(1.0)/CoFeB(1.2)/MgO(1)/Ta (thickness in nanometer) Hall bar device and corresponding measurement configuration. (b)
Hall resistance (RHall) v.s. perpendicular magnetic field (Hz) for the proposed device with varying tTa. (c) Current-induced magnetic switching with varying tTa. (d) Upper figure: macrosimulated Mz v.s. Jc with M1 tilting from +Z to +Y by 20 deg. but M2 lying perfectly along +Z direction; lower figure: simulated Mz v.s. Jc with M1 lying along + Z direction but M2
tilting from + Z to + Y by 20 deg. (e) micro-simulated switching of the proposed device; left: both M1 and M2 with (001) alignment; right: M1 with (001) but M2 with (0, cos5°, sin5°)
alignment. Snapshots of the magnetization reversal configurations corresponding to the two switching conditions, which were taken at ~4.9 ns (marked by vertical dashed lines).

Field free CoFeB/Ta/CoFeB SOT Devices Achieved by Modulating Spacer Thickness:Simulation and Experiment

Sputtering technique has been the choice for fabricating L10 FePt granular thin-film media for heat-assisted magnetic recording (HAMR). A variety of amorphous grain boundary materials have been studied extensively [1,2]. Among them, SiOx has been shown to facilitate columnar growth of FePt grains; however, its limitation on deposition temperature prevents high ordering. Amorphous carbon can yield high-temperature-enduring microstructure, however, with a limitation on grain height leveling to an aspect ratio ~1. Amorphous BN was also reported to affect the ordering of FePt [3]. In this paper, we report a study for creating a granular FePt-L10 film with crystalline BN grain boundaries that facilitate small grains with high aspect ratios and high ordering. By applying RF substrate bias with a substrate temperature of 700 oC, a microstructure of columnar FePt grains separated and wrapped around by hexagonal boron nitride(h-BN) layers is produced, as shown in Fig. 1(a). The spacing of the lattice fringes in grain boundaries is ~0.34 nm, close to that of h-BN basal planes (0.331 nm). The electron energy loss spectrum (EELS) shows the π* peak at 191.8 eV in the B-K edge, confirming the formation of turbostratic h-BN. Fig.1(e) shows columnar grains with an aspect ratio of ~1.85. A similar nanostructure was observed in FePt-Carbon film deposited with RF substrate bias, in which the graphite phase was likely formed in grain boundary regions. The covalent binding within the honeycomb structured nanosheets imparts the grain boundary materials high stability at high temperatures. This study provides an extendibility of FePt-based granular media to utilize partial crystalline grain boundary materials to improve microstructure. It also presents more understanding of why carbon and BN can maintain good grain isolation at quite high temperatures. 
**References** 
[1] A. Perumal, Y.K. Takahashi, K. Hono, L10 FePt-C Nanogranular Perpendicular Anisotropy Films with Narrow Size Distribution, 1 (2008) 101301.
https://doi.org/10.1143/apex.1.101301. 
[2] C. Xu, B. Zhou, T. Du, B.S.D.C.S. Varaprasad, D.E. Laughlin, J.-G. Zhu, Understanding the growth of high-aspect-ratio grains in granular L10
-FePt thin-film magnetic media, APL
Materials. 10 (2022). https://doi.org/10.1063/5.0089009. 
[3] B.H. Li, C. Feng, X. Gao, J. Teng, G.H. Yu, X. Xing, Z.Y. Liu, Magnetic properties and microstructure of FePt/BN nanocomposite films with perpendicular magnetic anisotropy,
Applied Physics Letters. 91 (2007). https://doi.org/10.1063/1.2798584. 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/07f5a5208e585f6f71b6c269715f7b17.png) 
Fig.1 (a) Plane-view HRTEM of FePt-hBN film, (b) FFT shows a ring pattern of h-BN (002), corresponding to a d-spacing of 0.33~ 0.35 nm; (c) and (d) grain size and center-to-center
pitch distance distributions; (e) cross-sectional TEM image of the 8-nm-thick FePt-hBN film grown on MgO seed layer. An order parameter of 0.84 was achieved with substrate
temperature around 700oC.

RF Biased sputtering induced formation of hexagonal boron nitride (h

Patterned FePt media solutions, such as Bit-Patterned Media (BPM) and Embedded Hardmask Patterning (EMP), have been proposed as alternative methods to improve Heat-Assisted Magnetic Recording areal density. Understanding etching mechanism of FePt material is important to warrent the low damage to the magnetic properties caused by micro-fabrication process. In this research, Reactive Molecular Dynamics (MD) modeling is carried out to study methanol (MeOH) plasma etch on L10-FePt media. The atomistic-level etch simulation process is divided into two sequential MD simulation steps: the radical-based reactive treatment step, followed by the ion-based physical etch step. Carbon-monoxide (CO) and H2 molecules are identified as the main etch precursors in methanol plasma interacting with substrate. Reactive interaction between CO/H2 radicals and Fe/Pt atoms is studied using bond-order ReaxFF force field with atomic charge calculation. Bond energy calculation shows the positively charged Fe and Pt and the negatively charged C atoms in CO molecules can form ionic carbonyl bonds that are shown more stable than Fe-Pt metallic bonds. As the result, it is found that the number of Fe(CO) and Pt(CO) carbonyl bonds are dominated among the new bonds produced after the reactive-treatment process. In the following physical etch step simulated with Ar or He ion bombardment, in comparison with FePt surface without CO/H2 treatment, the sputter yield of FePt can significantly improve by 2-4X on the samples with the CO/H2-treatment step. 
**References** 
[1] H. Wang, H. Zhao, P. Quarterman, and J.-P. Wang, Appl. Phys. Lett., vol. 102, no. 5, p. 052406, 2013 
[2] Patent: US10,347,467B2, J.-P. Wang, P. Quarterman and J. Zhu 
[3] LAMMPS - A flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales, Comp. Phys. Comm. (accepted 09/2021),
DOI:10.1016/j.cpc.2021.108171 
[4] J. Zhu, P. Quarterman, J.-P. Wang, AIP Advances 2017, 7 (5) , 056507. https://doi.org/10.1063/1.4977223 
![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/a01666868c95347f3bf6c30ec19d4fec.png) 
Figure 1. Number and types of carbonyl bonds created on FePt surface after CO/H2 exposure

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/535be17232038eb114b6084ff7a87b38.png) 
Figure 2. FePt sputter yield ( with Ar ions) comparison on CO/H2-treated and non-treated surface

Reactive Molecular Dynamics Modeling of Plasma Etching of L10 FePt Magnetic Media

The automotion of spin textures, where geometrical gradients are exploited to propagate localized magnetic states without the need of external stimuli, is a promising phenomenon for fast, low-power transmission of magnetic information, as previously demonstrated in planar nanowire systems [1]. Here, we show that automotion is an attractive mechanism in 3D nanowire circuits for the vertical interconnectivity of functional magnetic planes, alternative to the standard current-based spintronic effects normally employed to move spin textures. To showcase this new approach, we have prototyped 3D spiral nanowires by a combination of 3D-printing Focused Electron Beam Induced Deposition and physical vapor deposition methods [2, 3]. The magnetic devices (Fig. 1) are made of Permalloy and are 3 Î¼m tall, 150 nm wide, presenting curvature gradients of 0.09 Î¼m-2. Due to the high directionality of the physical deposition process, they have average thickness gradients of -5.3nm/Î¼m; this very large thickness gradient results to be the dominating mechanism responsible for 3D domain wall automotion, as micromagnetic simulations indicate. We have directly imaged the automotion of domain walls in the 3D spirals using â€œshadowâ€ X-ray photoelectron microscopy [4]. In these experiments, we nucleate a pair of domain walls at different locations within the spirals using external magnetic fields, and directly observe the evolution of the system as the field is reduced until reaching zero value (Fig. 2). The experiments show the successful automotion of the walls along the 3D interconnectors, and its competition with the intrinsic pinning present in the devices at localized regions. This work thus proposes and successfully demonstrates the automotion of spin textures as a viable effect to create 3D interconnected magnetic devices [5].

Domain Wall Automotion for Three Dimensional Magnetic Interconnectivity

Artificially made, geometrically frustrated arrays of interacting magnetic nanostructures offer a remarkable playground for exploring spin ice physics experimentally [1-3]. Initially designed to capture the low-energy properties of highly frustrated magnets [4,5], artificial spin ices became in the past decade a powerful lab-on-chip platform in which to investigate cooperative magnetic phenomena and exotic states of matter. Since their introduction about fifteen years ago, the interest in artificial spin ice systems largely broadened, and the term now covers a wide range of physical phenomena and systems extending well beyond artificial ice-like magnets. Besides fundamental works, many studies were also conducted recently on the applicability of artificial spin ice geometries in magnetic architectures, in which the micromagnetic degree of freedom, spin wave excitations or topological magnetic pseudo-charges for example are envisioned as carriers for information transfer, storage and processing [6-8]. The richness of this fast evolving research field is certainly the variety of expertises and scientific backgrounds gathered within a single community, with scientists working in different, sometimes separated, areas of condensed matter magnetism, spreading from nanomagnetism and spintronics to frustrated magnetism and statistical mechanics. In this presentation, recent advances in the field will be overviewed and potential routes for future works will be discussed. 

**References:** 

[1] C. Nisoli, R. Moessner and P. Schiffer, Rev. Mod. Phys. 85, 1473 (2013). 
[2] N. Rougemaille and B. Canals, Eur. Phys. J B 92, 62 (2019). 
[3] S. H. Skjærvø, C. H. Marrows, R. L. Stamps and L. J. Heyderman Nat. Rev. Phys. 2, 13 (2020). 
[4] M. Tanaka et al., J. Appl. Phys. 97, 10J710 (2005); Phys. Rev. B 73, 052411 (2006). 
[5] R. F. Wang et al., Nature 439, 303 (2006). 
[6] S. Gliga, E. Iacocca and O. G. Heinonen, APL Mater. 8, 040911 (2020). 
[7] M. T. Kaffash, S. Lendinez and M. B. Jungfleisch, Phys. Lett. A 402, 127364 (2021). 
[8] J. C. Gartside et al., Nat. Nanotech. 17, 460 (2022).

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