Six-fold in-plane magnetic anisotropy in Co-implanted ZnO (0001)

Magnetic anisotropies of Co-implanted ZnO (0001) films grown on single-crystalline Al2O3 (11-20) substrates have been studied by ferromagnetic resonance (FMR) technique for different cobalt implantation doses. The FMR data show that the easy and hard axes have a periodicity of 60 degrees in the film plane, in agreement with the hexagonal structure of the ZnO films. This six-fold in-plane magnetic anisotropy, which is observed for the first time in ZnO-based diluted magnetic semiconductors, is attributed to the substitution of cobalt on Zn sites in the ZnO structure, and a clear indication for long range ferromagnetic ordering between substitutional cobalt ions in the single-crystalline ZnO films.Comment: 7 pages, 4 figure

Magnetic Resonance Detection of Explosives and Illicit Materials

X, 168 p. 84 illus., 50 illus. in color.online re

Fe ve As Elementleri ile Katkılı Tetrahedritlerin Karakterizasyonu ve Fiziksel Özellikleri

Birçok sülfat tuzu mineralleri arasında, tetrahedrit/tennantit grubu, termoelektrik ve fotovoltaik gibi ileri teknoloji uygulamalarında umut verici bir yere sahip olduğundan dolayı araştırmacıların ilgisini çekmektedir. Bu çalışmada katıhal reaksiyon metodu hazırlanmış ve ayrı ayrı vakumlu kuartz tüplere kapatılmış (Cu12Sb4S13) tetrahedrit ana malzemesi, %50Sb %50As tetrahedrit/tennantit bileşiği (Cu12As2Sb2S13) ve Cu12Sb4S13 ana malzemesindeki Cu elementi yerine kısmi olarak Fe katkılanan bileşiğinin (Cu10Fe2Sb4S13) yapısal karakteristikleri X-ışını kırımı tekniği (XRD) analiz edilmiştir. Oluşan bileşiklerin morfolojileri taramalı elektron mikroskobu (SEM) ile görüntülenmiş ve buna bağlı enerji dağıtıcı X-ışını spektrometresi (EDX) ile oluşan kompozisyonun element oranlarının analizleri yapılmıştır. Bu bileşiklerin ayrıca manyetik özellikleri, titreşimli örnek manyetik ölçüm tekniği (VSM) ile incelenerek belirlenmiştir. Tüm örnekler paramanyetik özellik göstermekte olup manyetik moment eğrilerinde Curie yasası ile uyumlu davranış gözlemlenmiştir

Fe ve As Elementleri ile Katkılı Tetrahedritlerin Karakterizasyonu ve Fiziksel Özellikleri

Birçok sülfat tuzu mineralleri arasında, tetrahedrit/tennantit grubu, termoelektrik ve fotovoltaik gibi ileri teknoloji uygulamalarında umut verici bir yere sahip olduğundan dolayı araştırmacıların ilgisini çekmektedir. Bu çalışmada katıhal reaksiyon metodu hazırlanmış ve ayrı ayrı vakumlu kuartz tüplere kapatılmış (Cu12Sb4S13) tetrahedrit ana malzemesi, %50Sb %50As tetrahedrit/tennantit bileşiği (Cu12As2Sb2S13) ve Cu12Sb4S13 ana malzemesindeki Cu elementi yerine kısmi olarak Fe katkılanan bileşiğinin (Cu10Fe2Sb4S13) yapısal karakteristikleri X-ışını kırımı tekniği (XRD) analiz edilmiştir. Oluşan bileşiklerin morfolojileri taramalı elektron mikroskobu (SEM) ile görüntülenmiş ve buna bağlı enerji dağıtıcı X-ışını spektrometresi (EDX) ile oluşan kompozisyonun element oranlarının analizleri yapılmıştır. Bu bileşiklerin ayrıca manyetik özellikleri, titreşimli örnek manyetik ölçüm tekniği (VSM) ile incelenerek belirlenmiştir. Tüm örnekler paramanyetik özellik göstermekte olup manyetik moment eğrilerinde Curie yasası ile uyumlu davranış gözlemlenmiştir

Charging effect reduction in electron beam lithography and observation of single nanopillars on highly insulating substrates

Electron beam writing and imaging of nanoscale structures on highly insulating substrates severely suffer from charging effects, which cause reduction in pattern resolution, positioning precision, and imaging quality. Conductive layers deposited above or below the resist layer can effectively reduce charge accumulation, but often give rise to contamination impairing the physical and chemical properties of functional nanostructures. Here we deal with top and bottom contacted, sub-micron-sized nanopillars made from multilayer stacks comprising ferromagnetic and non-magnetic materials for the study of current-induced magnetization dynamics. We show how the charging effects in a previously established fabrication process for single-crystalline nanopillars by H. Dassow et al. (2006) [1] can be significantly reduced by using the bottom electrode layer as charge dissipater and only isolating and disconnecting the bottom electrodes from ground after the fabrication of the delicate nanopillar structure by electron beam lithography. The modified process is successfully applied to Co2MnSi/Ag/Co2MnSi(001) multilayer stacks grown on highly insulating MgO substrates. Ellipsoidal nanopillars with a cross-section of 75 × 120 nm2 reveal 2% giant magnetoresistance and angular dependent magnetization behavior due to the magnetic anisotropy of the elliptical nanomagnets

Coupling Sub-nanoliter BDPA Organic Radical Spin Ensembles with YBCO Inverse Anapole Resonators

We report the development and test of planar microwave Inverse Anapole Resonators (IARs) made of superconducting Yttrium Barium Copper Oxide (YBCO) for electron spin resonance spectroscopy on small samples. We first characterize our resonators in zero field and then by carrying out transmission spectroscopy on a diluted α,γ-bisdiphenylene-β-phenylally (BDPA) organic radical spin ensemble in an applied magnetic field. These IARs allow us to carry out electron spin resonance spectroscopy both in continuous-wave and pulsed-wave mode, and to estimate the spin memory time of BDPA. The comparison with the results obtained for the same sample on typical linear coplanar resonators shows an improvement by ≈2 - up to3 – orders of magnitude in spin sensitivity, with effective sensing volumes below 1 nanoliter. The best sensitivity we achieved is S≈10^7 spin/(Hz)^1/2 in the pulsed-wave regime. These results compare well with similar experiments reported in the literature

Ferromagnetic resonance in double perovskite epitaxial thin films of La2NiMnO6 on SrTiO3 and NdGaO3 substrates

Rameev, Bulat Z/0000-0003-0828-8312; Rameev, Bulat/0000-0003-0828-8312WOS: 000281153600057Ferromagnetic resonance (FMR) studies of epitaxial La2NiMnO6 (LNMO) thin films on (100) oriented SrTiO3 and (110) oriented NdGaO3 substrates at room temperature are presented. Observation of FMR spectra above the Curie temperature of this compound confirms the presence of magnetic ordering in LNMO thin films at room temperature. Best fitting of FMR spectra has been made on the assumption of the coexistence of two magnetic phases with different easy and hard axis periodicities in the film plane of LNMO. The spectra of the films on various substrates are characterized by different in-plane and out-of-plane symmetries, which indicates the existence of different epitaxial growth on the substrates with different crystal symmetries and orientations. (C) 2010 American Institute of Physics. [doi:10.1063/1.3481678]State Planning Organization of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [2009K120730]; Research Projects Commission of Gebze Institute of TechnologyGebze Teknik University [2009-A11]This work was supported by State Planning Organization of Turkey through the Project No. 2009K120730. F.M. is indebted to Research Projects Commission of Gebze Institute of Technology for supporting this work by the Grant No. 2009-A11