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Nanoscale, low-phase noise, tunable transmitter-receiver links are key for enabling the progress of wireless communi-cation. We demonstrate that vortex-based spin-torque nano-oscillators, which are intrinsically low-noise devices due to their topologically-protected magnetic structure, can achieve frequency tunability when submitted to local ion im-plantation. In the experiments presented here, the gyrotropic mode is excited with spin-polarized alternating currents and anisotropic magnetoresistance measurements yield discreet frequencies from a single device. Indeed, chromium-implanted regions of permalloy disks exhibit different saturation magnetisation than the surrounding, non-irradiated areas, and thus different resonance frequency, corresponding to the specific area where the core is gyrating. Our study proves that such devices can be fabricated without the need of further lithographical steps, suggesting ion irradiation can be a viable and cost-effective fabrication method for densely-packed networks of oscillators.

The aim of this study is to develop an analytical rubric to evaluate the writing skills of of 5th graders and to provide evidence of validity and reliability of the developed rubrics. Data were obtained from 22 teachers in Ankara and Denizli provinces in Turkey. For the validity study, the fit between experts about each criteria and definitions was evaluated with the percentage of simple agreement. The Kendall's W coefficient was calculated for inter-rater reliability and the percent agreement for intra-rater consistency was calculated. The findings of the study indicate that there is a high level of agreement among the experts on the appropriateness and adequacy of the criteria and the definitions in the DPA; there is a high level of consistency between the evaluations made by the same rater and different raters. The findings of the research have been discussed and suggestions have been made within the framework of the relevant literature. C1 [Bilican Demir, Safiye] Kocaeli Univ, Egitim Fak, Olcme & Degerlendirme ABD, Kocaeli, Turkey. [Yildirim, Ozen] Pamukkale Univ, Egitim Fak, Olcme & Degerlendirme ABD, Denizli, Turkey.

Purpose: The aim of the study was to investigate the extent students' learning strategies and reading enjoyment variables predicted PISA 2009 reading achievement, and to examine whether reading enjoyment had a mediator effect in the relationship between reading achievement and learning strategies. Methods: In this correlational study, Turkey PISA 2009 reading comprehension cognitive test and student questionnaires were used for data collection. Learning strategies and reading pleasure which was related to students' reading comprehension achievement were identified as predictive variables and index values of these variables were used. The data were analysed using hierarchical linear models (HLM). Findings: The results of the HLM analysis showed that the students who used control strategies more frequently had higher reading scores. Memorization was negatively associated with reading literacy and the elaboration strategies had no effect on achievement. Reading enjoyment was identified as a variable that improved students' reading performance. It was found out that control and elaboration strategies directly affected student's reading enjoyment whereas memorisation did not have such a direct effect. The results related to the indirect effect between variables showed that reading enjoyment had a partial mediator effect for the control strategy and had a full mediating effect for elaboration. Implications for Research and Practice: Teachers are encouraged to use deep learning strategies instead of surface learning strategies. Teachers can inform their students about what deep learning strategies are, why they are more effective than others, and how to use them. The think aloud technique can be used to show how this strategy can be used in daily life. (C) 2019 Ani Publishing Ltd. All rights reserved C1 [Tavsancil, Ezel] Ankara Univ, Fac Educ Sci, Ankara, Turkey. [Yildirim, Ozen] Pamukkale Univ, Fac Educ, Denizli, Turkey. [Bilican Demir, Safiye] Kocaeli Univ, Fac Educ, Kocaeli, Turkey.

The demand on high data transfer and storage capacities requires smaller devices to transmit or save data. Forming well-defined ferromagnetic and electrically conducting volumes within a non-magnetic and insulating matrix in the dimensions of several nanometers can pave a way to the production of such small devices. It has been demonstrated that the reduction of oxygen in Co₃O₄/Pd multilayers is possible via local proton irradiation resulting in ferromagnetic and conducting Co embedded in a nonmagnetic and insulating Co₃O₄ matrix [1]. However, the physical mechanism behind the ion irradiation-induced oxide reduction was not addressed clearly. There are two possible mechanisms suggested to play a role behind this oxide reduction. The first one is the chemical reduction of oxygen by reacting with implanted H+ ions, while the second possible mechanism is atomic displacements induced by ion irradiation. To address this issue, we analysed cobalt oxide thin films after irradiation with H+ and Ne+ ions at different doses. The irradiation parameters for Ne+ were chosen to give the same displacements per atom (dpa) as that of H+ which is required to reduce cobalt oxide. We also confined irradiated areas on the films in the range of microns to submicron, in order to ascertain the lateral distribution of oxygen after irradiation. We prepared single layer films of CoO (6-12nm) and Co₃O₄ (10nm) capped with Pt protection layers. Broad-beam H+ irradiations were performed at 0.3 keV for ion doses ranging from 10¹⁵ to 10¹⁷ ions/cm² on unpatterned films. After irradiation the films were characterized structurally and magnetically and compared to un-irradiated films. Extended films showed approximately 7% of the Co bulk metal saturation magnetization (MS) after irradiation at a dose of 5 x 10¹⁶ ions/cm² (fig. 1a inset). The increase is more pronounced with Co₃O₄ than CoO (fig. 1a). A sample was also prepared with a striped irradiation mask of 40 μm pitch. These films showed a higher magnetization after irradiation at lower doses as compared to unpatterned films, 0.14 MA/m for a dose of 10¹⁶ ions/cm² (striped) as opposed to 0.025 MA/m (extended) for a dose of 10¹⁷ ions/cm². Figure 1 (b) shows the effect of stripe width (0.5, 5, 10, 20 μm) on the resulting magnetization after H+ irradiation at the same energy with a dose of 10¹⁷ ions/cm². No clear correlation between stripe width and MS was seen in either oxide phase for stripes down to 0.5 μm. However, the CoO sample with 0.5 μm stripes and a thinner oxide thickness of 6 nm (gold line) as opposed to 12 nm exhibited larger MS after irradiation, indicating oxygen displacements occur in the first few nanometers of the oxide. We also performed 5 keV Ne+ irradiations with the helium-ion microscope (HIM) varying the ion dose from 10¹⁴ to 10¹⁶ ions/cm². After Ne+ irradiations magnetic force microscopy (MFM) images were taken along with a topography image in the remnant state (fig. 2). Starting from the ion dose of 5x10¹⁴ ions/cm², a magnetic contrast could be observed by MFM, suggesting that oxygen atoms were successfully removed locally by reducing paramagnetic CoO to ferromagnetic Co. The formation of topographical bubbles was observed upon increasing the ion dose from 10¹⁵ ions/cm² to 10¹⁶ ions/cm². The lateral and horizontal sizes of the observed bubbles show a clear dependence on the ion dose with a narrow size distribution. In conclusion, our results show that, oxygen removal by means of H+ irradiation is more efficient in Co₃O₄ films as opposed to CoO. Additionally, although there is little dependence of the resulting Ms on the pitch of the stripes (in the range of 0.5 - 20 μm), the use of a stripe mask has a more pronounced effect on the oxygen removal process as compared to the irradiations on extended films. Therefore, the physical mechanism behind the ion-irradiation induced oxide reduction process cannot purely be a chemical reaction between oxygen and hydrogen. As an outlook, the lateral size and spacing of the ferromagnetic regions generated by H+ irradiation is only limited by the resolution of EBL. This method and the successful formation of ferromagnetic regions upon Ne+ irradiation using the HIM can be exploited to print smaller, closer and synchronized contacts for nanocontact spin torque oscillators.

The fundamental oscillation mode of magnetic vortices in thin-film elements has recently been proposed for designing spin-torque-driven nano-oscillators [1]. Commercial applications require tuning of the output frequency by external parameters, such as applied fields or spin-polarized currents. However, the tunability of vortex-based devices is limited, since the gyrotropic frequency is specific to the individual sample design. Indeed, the fundamental frequency is known to be determined by the saturation magnetisation, M_s , as well as the geometrical confinement of the magnetisation, i.e. the diameter and height of the magnetic disk [2, 3]. Micromagnetic simulations [4] have shown that if regions with different saturation magnetisation can be induced in a magnetic disk, multiple precession frequencies can be generated. We show that ion implantation [5] is a novel route to fabricate such devices. Permalloy (Py) disks of various diameters and thicknesses were prepared using electron beam lithography followed by electron beam evaporation. Individual disks were contacted by gold leads to study the interaction of spin-polarized current with the magnetic vortex. The presence of vortex is verified by magneto optic Kerr effect (MOKE), X-ray magnetic circular dichroism (XMCD) and magnetotransport measurements. The magnetic field dependence of the vortex position can be tuned by the disk size as shown by XMCD (Figure 1 (a)). Higher magnetic stability due to larger annihilation fields can be achieved by smaller disk diameters, whereas larger field sensitivity is present in larger disks (Figure 1 (b)). Magnetotransport measurements on electrically contacted disks show the presence of anisotropic magnetoresistance (AMR) in different disks with varying thickness (Figure 1 (c)). Using a conventional lock-in technique, the resonance frequencies are measured for disks with different radii as shown in Figure 2 (a), with the inset showing the scanning electron microscope image of an electrically contacted disk. In order to modify the magnetisation within a single disk and to achieve two different oscillation frequencies, we implant chromium in different regions of the disk (inner and outer). Cr-implantation leads to a decrease in the Curie temperature and thus a reduction in the magnetic moment [6]. The reduction of M_s as a function of Cr fluence was optimised on extended Py films using a vibrating sample magnetometer – superconducting quantum interference device (VSM-SQUID), see figure 2 (b). A clear drop in M_s with increasing the chromium ion fluence is observed. Concentric donut-like structures were then implanted with Cr and the modification of dynamics as a function of magnetic field was investigated. An example of Cr implantation in a 3 µm radius disk at 30 keV with a fluence of 1.2×〖10〗^16 ions/cm^2 is shown in Figure 2 (c). The vortex core is shifted between the two different magnetisation regions by applying an external in-plane field. The vortex nucleates in the irradiated region at – 2.281 mT, leading to a resonance frequency of 30.2 MHz (shown in orange in Figure 2 (c)). Further increasing the external field pushes the vortex core to the non-irradiated region where the resonance frequency is 42.3 MHz (shown in green), corresponding to a field of + 1.597 mT. The results show that ion implantation is a novel way to obtain multiple frequencies from a single disk.

2018 Medical Technologies National Congress, TIPTEKNO 2018 -- 8 November 2018 through 10 November 2018 -- -- 144203, In this study, A user-friendly, versatile and easily accessible educational software design was done by using NEURON hoc programming in order to investigate the dynamics, biophysical properties of nerve cells and their responses to various stimulation. With the help of interfaces which prepared for users to be assisted visually, it is aimed to be able to easily perform almost any application desired. This software allows users to perform their simulations without the need to write any code. Considering the features given in detail in the study, it has been suggested to use the software in neuroscience education. © 2018 IEEE.