WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 1Citation - Scopus: 1Ferromagnetism Above 200 K in Organic-Ion Intercalated CrSBr(American Chemical Society, 2025) Ferreira-Teixeira, S.; Tezze, D.; Ramos, M.; Álvarez-García, C.; Bayındır, B.; Jo, J.; Gobbi, M.; 01. Izmir Institute of TechnologyCrSBr is a van der Waals magnetic semiconductor exhibiting antiferromagnetic order below 140 K. It has emerged as a promising platform for engineering 2D magnetism because its intertwined electronic, optical, and magnetic properties can be profoundly modified via external stimuli such as electrical gating or magnetic fields. However, other strategies for tuning magnetism in layered materials, such as molecular intercalation, remain largely unexplored for CrSBr. Here, we demonstrate that the intercalation of tetramethylammonium (TMA) and tetrapropylammonium (TPA) ions into CrSBr induces a transition from antiferromagnetic to ferromagnetic order, while significantly enhancing the magnetic transition temperature to 190 K (TMA) and 230 K (TPA). The resulting intercalates are air-stable and exhibit large, hysteretic magnetoresistance exceeding 60% at 50 K in the TPA case. Besides, intercalation introduces symmetry-breaking structural changes in each CrSBr plane, revealed by Raman microscopy and corroborated by density functional theory (DFT) calculations. These findings highlight molecular intercalation as a powerful and versatile route to tailor the magnetic properties of CrSBr and unlock its potential to fabricate robust, high-temperature 2D magnetic devices. © 2025 Elsevier B.V., All rights reserved.Article Citation - WoS: 4The Synthesis of Ferromagnetic La0.75ca0.25mno3 Nanowires by a Sol-Gel Method(National Institute of Optoelectronics, 2010) Atalay, Funda E.; Tarı, Süleyman; Yağmur, V.; Atalay, Selçuk; Kaya, Harun; Tarı, Süleyman; Avşar, D.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study, densely packed La0.75Ca0.25MnO3 (LCMO) nanowires were synthesized within a porous anodic aluminum oxide (AAO) template by means of a sol-gel method using nitrate as raw material and ethylene glycol as the chelating agent. It was observed from measurements of hysteresis curves that the magnetic behavior of the LCMO nanowire arrays was strongly dependent on the pH of the solution. As it has been reported that bulk polycrystalline La0.75Ca0.25MnO3 samples have a Curie temperature of 224 K [1], it is interesting to find that nanowires produced at pH 3 show ferromagnetic properties at room temperatureArticle Citation - WoS: 7Citation - Scopus: 7Mfm Imaging of Expanded Austenite Formed on 304 Ss and Cocrmo Alloys(Elsevier Ltd., 2014) Öztürk, Orhan; Fidan, Mehmet; Öztürk, Orhan; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyNew data related to the magnetic nature of the expanded austenite layers on CoCrMo and austenitic stainless steel by nitrogen plasma immersion ion implantation (PIII) are presented. Implantations were performed in the temperature range between 300 and 550°C for a fixed processing time of 1h. Magnetic properties, nitrogen distribution, implanted layer phases, and surface topography were studied with a combination of experimental techniques involving magnetic force microscopy, SIMS, XRD, SEM and AFM. As a function of the processing temperature, phase evolution stage for both alloys follows the same trend: (1) initial stage of the expanded phase formation, γN; (2) its full development; and (3) its decomposition into CrN precipitates and the Cr-depleted matrix, fcc γ-(Co, Mo) for CoCrMo and bcc α-(Fe, Ni) for 304 SS. MFM imaging reveals distinct, stripe-like ferromagnetic domains for the fully developed expanded austenite layers both on CoCrMo and 304 SS alloys. Weak domain structures are observed for the CoCrMo samples treated at low and high processing temperatures. The images also provide strong evidence for grain orientation dependence of magnetic properties. The ferromagnetic state for the γN phase observed here is mainly linked to large lattice expansions due to high N content.Article Citation - WoS: 11Citation - Scopus: 13Magnetic Layer Formation on Plasma Nitrided Cocrmo Alloy(Elsevier Ltd., 2011) Öztürk, Orhan; Okur, Salih; Okur, Salih; Öztürk, Orhan; Riviere, Jean Paul; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study structural and magnetic character of the expanded austenite phase (γN) layer formed on a medical grade CoCrMo alloy by a low-pressure Radio-Frequency plasma nitriding process was investigated. The formation of the expanded austenite phase is facilitated at a substrate temperature near 400°C for 1, 2, 4, 6 and 20h under a gas mixture of 60% N2-40% H2. The magnetic state of the γN layers was determined by a surface sensitive technique, magneto-optic Kerr effect (MOKE), and with a scanning probe microscope in magnetic force mode (MFM). Strong evidence for the ferromagnetic nature of the γN-(Co,Cr,Mo) phase is provided by the observation of stripe domain structures and the hysteresis loops. The ferromagnetic state for the γN phase observed here is mainly linked to large lattice expansions (~10%) due to high N contents (~30at.%). As an interstitial impurity, nitrogen dilates the host lattice i.e. the Co-Co (or Fe-Fe) distance is increased, which strongly influences the magnetic interactions. An analogy between the magnetic properties of the expanded phases, γN-(Fe,Cr,Ni) and γN-(Co,Cr,Mo), formed in austenitic stainless steel alloys and the CoCrMo alloy of this study is made, and it is suggested that the ferromagnetic states for the γN-(Co,Cr,Mo) and γN-(Fe,Cr,Ni) phases may be correlated with the volume dependence of the magnetic properties of fcc-Co/Co4N and fcc-Fe/Fe4N, respectively.Article Citation - WoS: 24Citation - Scopus: 29Thermal Stability of the High-N Solid-Solution Layer on Stainless Steel(Elsevier Ltd., 2002) Öztürk, Orhan; Öztürk, Orhan; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyLow-energy, high-flux N ion implantation into austenitic stainless steel held at approximately 400 °C results in dramatic improvements in the tribological properties due to sufficiently large N layer thicknesses and high-N-content solid solution phase. γN. In this paper, post-ion beam processing via isothermal annealing of a low-energy (0.7 keV), high-flux (2.5 mA/cm2) N implanted fee 304 stainless steel held at 400 °C has been investigated by Mössbauer spectroscopy and X-ray diffraction (XRD). Post-implantation annealing at 400 °C demonstrated the metastability and showed that the magnetic γN produced at lower ion energies and higher fluxes transformed systematically to a paramagnetic γN phase with less N content and less lattice expansion, thereby destabilizing the magnetic state of γN. The isothermal annealing results in much thicker γN layers but with less N in solid solution due to the N diffusion into the substrate. Based on the XRD data, the N diffusivity under isothermal annealing conditions is found to be D = 2X10-13 cm2/s at 400 °C, consistent with a model which explains that the trapping by Cr atoms in the stainless steel becomes more effective when N contents are low relative to the Cr concentration ( ~ 19 at.% in 304 stainless steel).