{"id":84,"date":"2021-07-18T22:10:11","date_gmt":"2021-07-18T22:10:11","guid":{"rendered":"https:\/\/phynd.polimi.it\/?page_id=84"},"modified":"2024-04-04T10:05:20","modified_gmt":"2024-04-04T10:05:20","slug":"research","status":"publish","type":"page","link":"https:\/\/phynd.polimi.it\/?page_id=84","title":{"rendered":"Research"},"content":{"rendered":"\n
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Phase Nanoengineering<\/strong><\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n\n\n

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Tools for controlling physics at the nanoscale are crucial for the development of new paradigms in optics, electronics and spintronics.  We develop advanced techniques based on thermal scanning probe lithography (t-SPL)<\/em><\/strong> and direct laser writing, for crafting the physical properties of materials<\/strong><\/em> via physical, structural or chemical modifications.<\/p>\n<\/div>\n\n\n\n

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Nanomagnetism & Magnonics<\/strong><\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n\n\n

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We develop and use thermally assisted magnetic nanopatterning and laser lithography<\/em><\/strong>, in combination with nanolithography,\u00a0for patterning multidimensional spin-textures<\/em><\/strong> in magnetic multilayers, such as domains, domain walls and topological solitons. Then, we use such spin textures for controlling and study the emission and propagation of spin waves<\/em><\/strong> in magnetic thin films. We study the three-dimensional propagation of spin waves<\/strong><\/em> in multilayers<\/p>\n<\/div>\n\n\n\n

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Nanoelectronics & Quantum Materials<\/strong><\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n\n\n

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We control at the nanoscale the electronic and spin transport properties<\/em><\/strong> of thin-films in phase-change materials and complex oxides, and develop new artificial nanomaterials and devices with engineered electronic transport properties, arising from the proximity and coexistence of different structural and electronic phases.<\/p>\n<\/div>\n<\/div>\n\n\n\n


Advanced Nanofabrication and Phase Nanoengineering<\/h3>\n\n\n\n
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Nanomaterials acquire novel physical properties which derive from their specific nanostructure, or reduced dimensionality, and which can be markedly different from the properties of their bulk counterpart. Phase-nanoengineering (Figure 1) is based on directly inducing highly localized, tunable and stable modifications to the physical properties of materials via exposure with a highly localized energy source.<\/em><\/strong><\/p>\n\n\n\n

We use a highly localized energy source to irradiate point-by-point the material and induce controlled phase transitions, compositional or structural modifications.<\/strong><\/em> By tuning the energy source while scanning the sample, we control point-by-point the degree of modification, creating \u201cgrayscale\u201d profiles which in turn lead to highly controlled physical properties. This goes beyond the capabilities of most conventional nanofabrication methodologies, which in most cases allow for binary patterns characterized by the presence or absence of the material. <\/p>\n<\/div>\n\n\n\n

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The direct-writing process also has the advantage of not requiring to place the sample in contact with harsh chemicals, and of leaving completely untouched the non-patterned regions. This aspect is critical when dealing with sensitive materials, or in general materials which are not compatible with standard lithographic processes.<\/p>\n\n\n\n

Depending on the geometry and properties of the energy landscape, with respect to the typical physical length-scales in play, widely different effects can be achieved.<\/strong><\/em> Periodic energy landscapes, such as the 1-D modulation shown in figure, can give rise to \u201cgrayscale\u201d metamaterials such as magnonic or photonic crystals. Highly localized potentials on the other hand provide the basic building blocks for realizing nanoelectronic circuitry, e.g. nanowires, nano-islands, gates. Similarly, in the case of waves, sharp property modulations, such as the refractive index in optics or the magnetic properties in magnonics allow confining effects, among which waveguiding, or tailored wave emission.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Figure 1.<\/strong> Schematic of phase-nanoengineering.<\/strong> Top: As grown two-dimensional thin films, mono-dimensional nanowire arrays and zero-dimensional arrays of nano-dots. They possess spatially uniform physical properties. Bottom: Materials after the phase-nanoengineering patterning corresponding to the 2D-1D-0D dimensionality above. The phase-nanoengineering process is sketched. A highly localized energy source is scanned on the sample and produces point-by-point controlled modifications to the physical properties of the material. The color code indicates the \u201cgrayscale\u201d energy landscape realized within the material. Examples of potential landscapes patterned via phase-nanoengineering. V. Levati et al., Advanced Materials Technologies, 2023<\/em><\/figcaption><\/figure>\n\n\n\n
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We develop and use Phase nanoengineering is performed via either Thermal Scanning Probe Lithography (tSPL, Figure 2) and Direct Laser Writing (DLW).<\/em><\/strong> In the first case, a nanometric heated Atomic Force Microscope tip is scanned over the sample surface, locally heating the surface controllably and sequentially. Its advantages are the sub-10 nm spatial resolution, high degree of tunability of the tip temperature,<\/p>\n<\/div>\n\n\n\n

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from room temperature up to about 1200\u00b0C , and flexibility for a wide range of materials and applications. DLW on the other hand provides higher peak powers compared to tSPL, and diffraction-limited spatial resolution. By combining and developing the two techniques, a wide range of systems ranging from magnetic materials, to 2D and quantum materials can be investigated.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Figure 2. Thermal Scanning Probe Lithography set-up.<\/strong> Thermal scanning probe lithography (tSPL) set-up using a customized atomic force microscope (AFM). AFM scanners and feedback system allow sweeping of the heated probe in contact with the sample. The temperature of the probe is controlled by tSPL electronics during scanning. Thermal probe, consisting of a U-shaped cantilever with two conductive legs, and a resistive heater located above the nanometric probe tip. E. Albisetti et al., Nature Reviews Methods Primers, 2022<\/em><\/figcaption><\/figure>\n\n\n\n

Selected references<\/strong><\/h4>\n\n\n\n

E. Albisetti, A. Cal\u00f2, A. Zanut, X. Zheng, G.M. de Peppo, and E. Riedo, \u201cThermal scanning probe lithography<\/a>\u201d, Nature Reviews Methods Primers<\/em> 2, 32 (2022).<\/p>\n\n\n\n

E. Albisetti, D. Petti, R. Bertacco, E. Riedo, \u201cMagnetic nanopatterning via thermal scanning probe lithography\u201d, Book chapter in \u201cNanofabrication<\/a>\u201d, Edited by Jos\u00e9 Maria De Teresa, IOP Publishing (2020).<\/p>\n\n\n\n

E. Albisetti, D. Petti, M. Pancaldi, M. Madami, S. Tacchi, J. Curtis, W. P. King, A. Papp, G. Csaba, W. Porod, P. Vavassori, E. Riedo, R. Bertacco, \u201cNanopatterning reconfigurable magnetic landscapes via thermally assisted scanning probe lithography<\/a>\u201d, Nature Nanotechnology<\/em>, 11 (6), 545\u2013551 <\/a>(2016).<\/p>\n\n\n\n

X. Zheng, A. Cal\u00f2, E. Albisetti, X. Liu, A. S. M. Alharbi, G. Arefe, X. Liu, M. Spieser, W. J. Yoo, T. Taniguchi, K. Watanabe, C. Aruta, A. Ciarrocchi, A. Kis, B.S. Lee, M. Lipson, J. Hone, D. Shahrjerdi, E. Riedo, \u201cDirect metal contacts on MoS2 with vanishing Schottky barrier via thermal nanolithography<\/a>\u201d, Nature Electronics<\/em>, 2, <\/em>17\u201325 (2019).<\/p>\n\n\n\n

X. Zheng, A. Cal\u00f2, T. Cao, X. Liu, Z. Huang, P. M. Das, M. Drndic, E. Albisetti, F. Lavin, T. Li, V. Narang, W. P. King, J. W. Harrold, M. Vittadello, C. Aruta, D. Shahrjerdi, E. Riedo, \u201cSpatial defects nanoengineering for bipolar conductivity in MoS2<\/sub><\/a>\u201d, Nature Communications,<\/em> 11, 1\u201312 (2020).<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Nanomagnetism and Magnonics<\/h3>\n\n\n\n
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Spin textures in magnetic materials, such as magnetic domains, domain walls or skyrmions, are extremely interesing for their potential as active components in data storage and processing devices.<\/em><\/strong> The interest arises from their scalability towards nanoscale dimensions, resilience against external perturbations and high degree of tunability via external stimuli. For example, racetrack memories are based on storing and manipulating information in domain walls or skyrmions, which are controllably stabilized and manipulated in ferromagnetic nanowires. Also, the dynamic properties of spin textures, i.e. their excitations, and the way they interact with spin waves, i.e. propagating magnetic excitations, are a very active field of reasearch for both fundamental science and applications in technology. With the rising of spin textures, and the discovery of complex textures in ferromagnets and antiferromagnets alike, the importance of controlling their properties and configuration has become crucial.<\/p>\n<\/div>\n\n\n\n

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Recently, we introduced a novel technique, thermally assisted magnetic scanning probe lithography (tam-SPL), to write nanoscale reconfigurable spin-textures in a continuous and homogeneous film.<\/em><\/strong> In tam-SPL, we use the heatable tip of a scanning probe microscope, in presence of a magnetic field, to heat the portion of the film in contact to the tip and then we exploit the cooling due to heat dispersion when the tip is moved to another position. This confined \u201cfield cooling\u201d causes a local pinning of the magnetization of the FM along the direction of the applied magnetic field, which reflects in a shift of its hysteresis loop. This method allows writing of arbitrary shaped spin-textures such as magnetic domains, domain walls or solitons, with controlled magnetic anisotropy and spin-orientation (Figure 3 a-c). The patterned spin textures can be modulated via external fields but, importantly, are stable at remanence and cannot be permanently erased with magnetic fields.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Figure 3. Thermally assisted magnetic scanning probe lithography and applications in magnonics.<\/strong> a.<\/strong> Thermally assisted magnetic scanning probe lithography (tam-SPL). Spin textures are stabilized by sweeping the heated probe, on a ferromagnet\/antiferromagnet bilayer, in the presence of an external magnetic field Hw. Red arrows indicate magnetization in the ferromagnetic layer, blue\/purple arrows indicate spins in the antiferromagnetic layer. b.<\/strong> Patterned magnetic domainsimaged using magnetic force microscopy (MFM). Arrows indicate direction of magnetization in the pattern (Mpat) and in the background (Mbg). Scale bar: 2\u03bcm. c.<\/strong> Micromagnetic simulations showing magnetization (black arrows) of diamond-shaped magnetic domain in part b. d.<\/strong> Domain wall-based waveguide for spin waves. Spin waves are emitted by the antenna (yellow) and propagate within the domain wall. e.<\/strong> Domain wall-based nanoantenna for spin waves. Domain wall, set in oscillation, emits shaped spin wave wavefronts. f.<\/strong> Experimental X-ray microscopy snapshot showing curved spin wave wavefronts emitted by domain wall (thick red line). Scale bar: 500nm. E. Albisetti et al., Nature Reviews Methods Primers, 2022<\/em><\/figcaption><\/figure>\n\n\n\n
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The precise control of the magnetization allows for various applications. Among these, <\/em><\/strong>manipulating spin waves using patterned spin textures is an extremely promising strategy.<\/strong><\/em> Indeed, spin waves are being extensively studied as a potential platform for beyond-CMOS computing, owing to their rich phenomenology, energy efficiency and nanoscale dimensions. In figure 3 d-f we show two applications in this field. In (d), tam-SPL spin textures are used as waveguides for confining and steering spin waves on-chip, and for building the basic building blocks for reconfigurable circuits.<\/p>\n<\/div>\n\n\n\n

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In (e-f), on the other hand, domain walls in a synthetic antiferromagnt are used as magnonic nanoantennas for emitting shaped spin-wave wavefronts. Further applications are envisioned; for example, patterning of out-of-plane magnetized materials and 3D spin textures, and the realization of magnon-based computing platforms that exploit spin-wave interference in continuous films.<\/p>\n<\/div>\n<\/div>\n\n\n\n

Selected references <\/h4>\n\n\n\n

D. Petti, S. Tacchi, and E. Albisetti, \u201cReview on magnonics with engineered spin textures<\/a>\u201d, Journal of Physics D: Applied Physics<\/em>, 55, 293003 (2022).<\/p>\n\n\n\n

A. Barman, G. Gubbiotti, S. Ladak, A. O. Adeyeye, M. Krawczyk, J. Gr\u00e4fe, C. Adelmann, Sorin Cotofana, A. Naeemi, V. I Vasyuchka, B.Hillebrands, SA Nikitov, H. Yu, D. Grundler, A. Sadovnikov, A.A. Grachev, S.E. Sheshukova, J.-Y. Duquesne, M. Marangolo, G. Csaba, W. Porod, V.E. Demidov, S. Urazhdin, S. Demokritov, E. Albisetti, D. Petti, R. Bertacco, H. Schulteiss et al., \u201cThe 2021 Magnonics Roadmap<\/a>\u201d, Journal of Physics: Condensed Matter<\/em>, 33, 413001 (2021).<\/p>\n\n\n\n

E. Albisetti, S. Tacchi, R. Silvani, G. Scaramuzzi, S. Finizio, S. Wintz, C. Rinaldi, M. Cantoni, J. Raabe, G. Carlotti, R. Bertacco, E. Riedo, D. Petti, \u201cOptically Inspired Nanomagnonics with Nonreciprocal Spin Waves in Synthetic Antiferromagnets<\/a>,\u201d Advanced Materials<\/em>, 32, 1906439 (2020).<\/p>\n\n\n\n

E. Albisetti, D. Petti, G. Sala, R. Silvani, S. Tacchi, S. Finizio, S. Wintz, A. Cal\u00f3, X. Zheng, J. Raabe, E. Riedo, R. Bertacco \u201cNanoscale spin-wave circuits based on engineered reconfigurable spin-textures<\/a>,\u201d Communications Physics<\/em>, 1, 56 (2018).<\/p>\n\n\n\n

E. Albisetti, D. Petti, R. Bertacco, E. Riedo, \u201cMagnetic nanopatterning via thermal scanning probe lithography\u201d, Book chapter in \u201cNanofabrication<\/a>\u201d, Edited by Jos\u00e9 Maria De Teresa, IOP Publishing (2020).<\/p>\n\n\n\n

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Nanoelectronics & Quantum Materials<\/h3>\n\n\n\n

Work in progress..<\/p>\n","protected":false},"excerpt":{"rendered":"

Tools for controlling physics at the nanoscale are crucial for the development of new paradigms in optics, electronics and spintronics.  We develop […]<\/p>\n","protected":false},"author":3,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-templates\/page_fullwidth.php","meta":{"_crdt_document":"","footnotes":""},"class_list":["post-84","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=\/wp\/v2\/pages\/84","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=84"}],"version-history":[{"count":52,"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=\/wp\/v2\/pages\/84\/revisions"}],"predecessor-version":[{"id":2083,"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=\/wp\/v2\/pages\/84\/revisions\/2083"}],"wp:attachment":[{"href":"https:\/\/phynd.polimi.it\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=84"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}