Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture Test lecture 

Jana test lecture

Here, we test whether the perception of liquids is based on abstract, physics-based representations. To do so, we use a novel behavioral task that requires generalization across scene configurations. We created 30 animations of liquids flowing through and interacting with surfaces and objects. These animations came from six qualitatively different scene configurations and five viscosity levels. During the experiment, participants viewed two liquid animations (side-by-side), each from a different scene configuration, and they rated the similarity of underlying viscosities. We found that not only average similarity ratings are linearly predicted based on true viscosity differences, but also the identity of the scene configuration pairs was uncorrelated to similarity ratings. This successful generalization in human behavior suggests an underlying abstract, physics-based representation of liquids. We also present a new probabilistic model of liquid perception that accounts for behavioral ratings, quantitatively supporting our hypothesis.

Perception of liquids relies on generalizable, physics-based representations

This work describes high performance TiO2 thin film transistors using TiO2 as the gate dielectric and channel materials. Bilayer dielectric with high conduction band offset is needed for further enhacing the device performance when TiO2 is used as part of the gate dielectric.

High-performance TiO2 thin film transistors using TiO2 as both channel and dielectric

we have developed a compact model for Trap Assisted Tunneling (TAT) based GIDL leakage, and highlighted that only BTBT (Band-to-Band-Tunneling) is not
enough to capture the physical trends of GIDL, and TAT is the essential physical mechanism at the advanced technology
nodes.

Compact Model for Trap Assisted Tunneling based GIDL

In this work, we demonstrate atomic-layer-deposited (ALD) single-channel indium oxide (In2O3) gate-all-around (GAA) nanoribbon field-effect transistors (FETs) in a back-end-of-line (BEOL) compatible process. A maximum on-state current (ION) of 19.3 mA/μm (near 20 mA/μm) is achieved in an In2O3 GAA nanoribbon FET with a channel thickness (T¬IO) of 3.1 nm, channel length (Lch) of 40 nm, channel width (Wch) of 30 nm. The record high drain current is about one order of magnitude higher than any conventional single-channel semiconductor FETs.

Late News: A Gate-All-Around Single-Channel In2O3 Nanoribbon FET with Near 20 mA/µm Drain Current

In recent years we have been focused on the understanding of magnetism in ensembles of 4f metallic nanoparticles (NPs) (R = Tb,Nd, Gd-M = Cu, Al, Y, La). As a result, we have reported that the existence of an ordered magnetic core and a disordered magnetic shell is regularly found in those ensembles. Depending on the stoichiometry (in our case, RX2) it is possible to easily tune the RKKY interactions to provoke the appearance of ferromagnetic or antiferromagnetic (AF) order within the NPs. Moreover, the fact that we are dealing only with thousand of moments per particle leads to use the super- prefix to define correctly the magnetic behaviour [1]. Besides, it is an upsetting fact that both the collective moment dynamics and the role of the crystalline electric field (CEF) in ensembles of NPs have barely been unearthed. To fill in this gap, we are reporting here a complete neutron-based study (Neutron Diffraction, ND, Small-Angle Neutron Scattering, SANS, and INS) on NdCu2 NPs (&lt;D&gt;≈13nm) to depict the skyline of order and disorder at the nanoscale. ND measurements (LLB) point to that the bulk commensurate AF structure is retained within the core. SANS confirms the survival of the AF within the nanoscale, together with a strong emergence of disorder, in the form of a rise in the low-Q region (Q&lt;0.665 Å-1). Magnetic measurements indicate the interactions among the surface moments strong enough to establish a Spin Glass behaviour, leading therefore to a Superantiferromagnetic state. Regarding the CEF panorama, macroscopic specific heat analyses anticipate a broad Schottky contribution, with a maximum located at T∼25 K. Then, microscopic INS measurements (ILL) performed at T=10K (paramagnetic) and T=1.5K (magnetic state) reveal that the splitting of the CEF levels, as well as the spin–wave excitations that emerged below the Néel transition (TN ≈ 6 K) in polycrystalline NdCu2 [2] are maintained in the NPs. Furthermore, we have been able to isolate the INS from the surface, which has allowed us to unravel the role of finite–size effects and microstrain. These two effects lead to a partial inhibition of the transitions from the ground state to the first excited level, as well as a stiffening of the magnon modes [3].

Order and disorder : The magnetic and crystalline electric field skyline of NdCu2 nanoparticles

The extent of magnetic ordering in highly-frustrated thermally active artificial kagome spin ice is limited by the lowest achievable blocking temperature, as the moments freeze before ordering is achieved [1]. A more substantial degree of magnetic ordering can be achieved by either lowering the blocking temperature of the individual nanomagnets or by increasing the critical transition temperature of the system. First, we pursue an approach of introducing interfacial Dzyaloshinskii-Moriya interactions (DMI), which lowers the blocking temperature by a factor of five, while keeping the transition temperature unchanged [2]. We demonstrate that a seven-ring kagome structure consisting of 30 nanomagnets with DMI can be thermally annealed into its ground state. Furthermore, the spin-ice correlations extracted from extended kagome lattices are found to exhibit the quantitative signatures of long-range charge-order, thereby giving experimental evidence for the theoretically predicted continuous transition to a charge-ordered state. Second, we find that slight modifications of the nanomagnets at the vertices in the artificial kagome ice allow us to control the energy landscape which leads to an increase of the critical temperatures [3]. These results provide paths for the tuning of magnetic ordering in artificial spin systems.

Long-range Magnetic Ordering in Artificial Kagome Spin Ice

Spin-crossover (SCO) complexes form an interesting class of switchable materials that can exist in two different spin states, known as the low-spin (LS) and high-spin (HS) states. These complexes may be switched between the two spin states under various stimuli including temperature, pressure, light, magnetic and electrical fields [1]. Among these stimuli, pressure is one of the most appealing thermodynamic parameters used to probe the spin transition properties of spin-crossover materials since it allows for tuning both the crystal field as well as the interactions between SCO centers. Since the pioneering works of Drickamer [2], Konig [3] and Gutlich[4], the pressure effect has continuously attracted the interest of the scientific community, being intensively studied until nowadays. In general, the application of an external pressure induces a transformation of the SCO complex to the low-spin state, i.e. to the state of lower molecular volume, and has the effect of shifting the switching temperatures towards higher values. However, the interpretation of the pressure effect on molecular SCO phenomena has been, in some cases, compromised by the relatively poor or incomplete information resulted from experimental difficulties related to the need for hydrostatic conditions at low temperatures. In this work I will talk on both hydrostatic [5, 6] and non-hydrostatic [7] pressure effects on the spin transition properties of molecular spin crossover complexes in terms of major thermal hysteresis loop and FORC diagram methods. We have shown that for high pressure gradients, the thermal hysteresis loop becomes asymmetric. Remarkably, the FORC diagram method has been proved to be much more sensitive to local changes than the “bulk” parameters, which characterize the major hysteresis loop. This makes the FORC diagram method a suitable technique to characterize the hydrostaticity degree of a pressure cell. Acknowledgements. This work was partially funded by UEFISCDI, project number PN-III-P1-1.1-TE-2019-2194 (Contract No: TE 123/2020)

Pressure effect on spin-crossover materials: Experiment vs theory

In the present work, we combine magnetometry and magnetic small-angle neutron scattering to study the influence of the microstructure on the macroscopic magnetic properties of a nanocrystalline Ni bulk sample, which was prepared by straining via high-pressure torsion. As seen by magnetometry, the mechanical deformation leads to a significant increase of the coercivity compared to nondeformed polycrystalline Ni. The neutron data reveal a significant spin-misalignment scattering caused by the high density of crystal defects inside the sample, which were created by the severe plastic deformation during the sample preparation. The corresponding magnetic correlation length, which characterizes the spatial magnetization fluctuations in real space, indicates an average defect size of 11 nm, which is smaller than the average crystallite size of 60 nm. In the remanent state, the strain fields around the defects cause spin disorder in the surrounding ferromagnetic bulk, with a penetration depth of around 22 nm. The range and amplitude of the disorder is systematically suppressed by an increasing external magnetic field. Under certain assumptions, the analysis of the penetration depth allows one to determine the magnitude of the effective magnetic anisotropy. For HPT Ni, we find an increased anisotropy (factor of 4), presumably due to magnetoelastic interactions, relative to the single-crystalline ground state. Our findings are supported and illustrated by micromagnetic simulations, which, for the particular case of nonmagnetic defects (holes) embedded in a ferromagnetic Ni phase, further highlight the role of localized spin perturbations for the magnetic microstructure of defect-rich magnets such as high-pressure torsion materials. This work was supported by the financial support from the National Research Fund of Luxembourg (Pride MASSENA Grant No. 10935404 and CORE SANS4NCC Grant), from KAKENHI (Grant No. 19K05102) and from the Japan Science and Technology Agency (Grant No. JPMJSK1511).

Revealing defect-induced spin disorder in nanocrystalline

Abstract Grain boundary diffusion (GBD) provides a promising way for Nd-Fe-B magnets to obtain high coercivity with less consumption of critical rare earths (RE). With the expansion of application field, the mechanical and anti-corrosion properties of Nd-Fe-B magnets has attracted increasing attention except their magnetic properties. Here, we proposed a strategy to simultaneously enhance these properties by GBD without employing heavy rare earths (HRE). The diffusion sources of Pr70Al20Cu10 (PrAlCu) and Al75Cu25 (AlCu) were prepared by arc melting. The thickness of initial magnet is 4.5 mm. The results show that the coercivity can be enhanced from 1000 to 1346 and 1089 kA/m by diffusion of PrAlCu and AlCu, respectively (Fig. 1(a)). Interestingly, the compression strength of the magnets also increased by 485 and 252 MPa, respectively. In addition, it is found that AlCu diffusion can improve the corrosion resistance of the magnets, which is different from that of PrAlCu [1]. The microstructure analysis showed that PrAlCu diffusion leads to the formation of continuous grain boundary (GB) layers for magnetic decoupling and strong binding between 2:14:1 grains (Fig. 1(b)). Although the non-RE diffusion source of AlCu shows less efficiency in increasing the content of RE-rich GB phases (Fig. 1(c)), it reduces the defects at interfaces, which is helpful for hindering the reversal domain nucleation [2, 3], as shown in Figs. 1(d1) to (d3). The modified GBs by AlCu diffusion also are effective for crack bridging or buffering, and exhibit an enhanced chemical stability. The high-abundance elements La/Ce based diffusion sources are also investigated in this work. The present results indicate that GBD of the HRE-free low-melting alloys can be used to effectively improve both the magnetic and service performance of Nd-Fe-B magnets due to the optimized microstructure.

![](https://assets.underline.io/uploads/markdown_image/1/image/1d95088594a90e4bd612c377f5970c41.jpg)

A strategy to enhance magnetic and service performance of Nd-Fe-B magnets by HRE-free grain boundary diffusion

We study the effect of thermal fluctuations on dipole coupled mesospins, the building blocks of artificial spin ice (ASI), in a micromagnetic framework. Taking into account the internal magnetic texture, we focus specifically on the fluctuations at the edges, which have previously shown to exhibit a temperature dependent switching between two states that are essentially half of a C- or S-state [1]. We study two different systems, the first being a system of two coupled magnets and the second being a fourfold coordinated ASI vertex. For the two mesospin system with parallel magnetization, we find magnonic mode splitting at the edges, which is relatively unaffected by temperature. When the magnetization in the two mesospins is opposite, we find the appearance of an asymmetric potential, which can be quantified through the magnetic texture correlations. The Arrhenius law is used to find the attempt frequency and the energy barriers associated with switching, the latter are found to be inversely proportional to the spacing. We find a logarithmic dependence of the attempt frequency on the energy barrier, which is indicative of entropy-energy compensation at small spacings (large barriers). The temperature dependent edge dynamics for the ASI vertex is evaluated for the four different types (Type I-IV), each displaying their own characteristic dynamics. An example of such dynamics is the collective switching of the handedness associated with the perpendicular edge magnetization in a type IV vertex configuration. These results indicate the presence of rich texture dynamics, even at the level of the individual building blocks of the ASI.

Magnetic Texture Fluctuations in Coupled Mesospin Systems

Ensemble magnetization of magnetic nanoparticles (NPs) has a sensitive dependence on the structural arrangement of particles. To better understand the correlation between spatial positions of NPs and ensemble magnetization, an experimental system is needed where particle position can be adjusted while simultaneously probing nanoscale magnetization. Here, we describe experiments using polarization analyzed small angle neutron scattering (PASANS) to study the change in magnetic correlations of ~7 nm iron oxide (Fe3O4) NPs embedded in stretched silicone rubber. PASANS is a powerful tool for mapping both the inter- and intra- particle magnetization of NPs on length scales ranging from 0.1 – 100 nm. The magnetic NP polymer gel, or magnetogel, can be stretched on the neutron beamline during an experiment. The macroscopic stretching is accompanied by nanoscale deformations, where polymer chains move to accommodate a new equilibrium configuration. NPs embedded in the gel change their configuration as a function of applied stress, providing a method to adjust the average center-to-center spacing between particles. The scattering data from the unstretched gel in a 1 T applied magnetic field can be modelled by 7.4 nm iron oxide NPs assembled in a hard sphere packing with 30% volume fraction. When the sample is stretched 3x its original size in a direction parallel to the applied field, the morphology changes dramatically. Specifically, the data can be described using a cluster model where NP dimers have emerged (Figures 1a and 1b). Stretching causes the particles to morph from semi-close packed, but individual, 7.4 nm diameter NPs into dimer-like clusters that are 15 nm long, as viewed perpendicular to the applied field (Figures 2a and 2b). These PASANS experiments clearly demonstrate that stretching the magnetogel modulates the structural characteristics of magnetic NPs in a pronounced, controllable manner.

![](https://assets.underline.io/uploads/markdown_image/1/image/39e948b29d4a9faea0cd8a27867ee2bb.jpg)

Fig. 1: Magnetic scattering from (a) unstretched and (b) 3x stretched gel in a 1 T field. The data set in (a) is fit to a hard sphere-like packing and (b) is fit to a model containing dimers

![](https://assets.underline.io/uploads/markdown_image/1/image/5b350fa63e4727cecd3c135d0fb252f5.jpg)

Fig. 2: Schematic showing rearrangement of NPs in (a) unstretched and (b) 3x stretched configurations.

Underline digital video library

Jana test lecture

Perception of liquids relies on generalizable, physics-based representations

High-performance TiO2 thin film transistors using TiO2 as both channel and dielectric

Compact Model for Trap Assisted Tunneling based GIDL

Late News: A Gate-All-Around Single-Channel In2O3 Nanoribbon FET with Near 20 mA/µm Drain Current

Order and disorder : The magnetic and crystalline electric field skyline of NdCu2 nanoparticles

Long-range Magnetic Ordering in Artificial Kagome Spin Ice

Pressure effect on spin-crossover materials: Experiment vs theory

Revealing defect-induced spin disorder in nanocrystalline

A strategy to enhance magnetic and service performance of Nd-Fe-B magnets by HRE-free grain boundary diffusion

Magnetic Texture Fluctuations in Coupled Mesospin Systems

Magnetic Correlations of Iron Oxide Nanoparticles as Probed by PASANS in Stretched Magnetogel Composites

Stay up to date with the latest Underline news!

PRESENTATIONS

CONFERENCES

COMPANY

RESOURCES