共查询到20条相似文献,搜索用时 15 毫秒
1.
Z.H. Han J.I. Budnick W.A. Hines P.W. Klamut M. Maxwell B. Dabrowski 《Journal of magnetism and magnetic materials》2006
In order to investigate the Ru sublattice magnetic structure, a study of the field dependence of the 99,101Ru nuclear magnetic resonance (NMR) has been carried out on the magnetic superconductor RuSr2GdCu2O8. It is found that the 99,101Ru NMR signal intensity increases significantly with applied magnetic field up to ≈3 kOe, beyond which, it progressively decreases. In addition, a shift of the NMR peaks to lower frequency is observed to begin at ≈1.3 kOe. These behaviors are shown to be accompanied by a field-induced Ru moment spin-flop in the ab planes, and are understood in terms of a previously proposed type-I antiferromagnetic ordering for the Ru sublattice. Based on this model, the inter-plane antiferromagnetic exchange coupling is determined to be ≈1.8 kOe along with a reversible in-plane spin-flop which is characterized by a field ≈0.6 kOe. 相似文献
2.
Epitaxial Ni80Fe20(5 nm)/Ru(x nm)/Ni80Fe20(5 nm) trilayers with thickness x = 0.5-3.0 were prepared on Al2O3 substrate. The structure, magnetic properties and magnetic depth profiles of the epitaxial Ni80Fe20(1 1 1)/Ru(0 0 0 1) multilayers were studied by X-ray diffraction, X-ray magnetic circular dichroism and polarized neutron reflectivity. A strongly enhanced orbital moment of Fe in the permalloy layer was observed at the Ru thickness of the first anti-ferromagnetic coupling, which might be due to an interference between two interfaces. At this Ru thickness, the neutron reflectivity data show a 0.8 nm layer at the interface with the magnetic moment perpendicular to the surface plane, which might be due to the enhanced spin-orbital coupling at interface. 相似文献
3.
Mitsuru Ohtake Kouhei Shikada Fumiyoshi Kirino Masaaki Futamoto 《Journal of magnetism and magnetic materials》2008
Co(0 0 0 1)hcp/Fe(1 1 0)bcc epitaxial magnetic bi-layer films were successfully prepared on SrTiO3(1 1 1) substrates. The crystallographic properties of Co/Fe epitaxial magnetic bi-layer films were investigated. Fe(1 1 0)bcc soft magnetic layer grew epitaxially on SrTiO3(1 1 1) substrate with two type variants, Nishiyama–Wasserman and Kurdjumov–Sachs relationships. An hcp-Co single-crystal layer is obtained on Ru(0 0 0 1)hcp interlayer, while hcp-Co layer formed on Au(1 1 1)fcc or Ag(1 1 1)fcc interlayer is strained and may involve fcc-Co phase. It has been shown possible to prepare Co/Fe epitaxial magnetic bi-layer films which can be usable for patterned media application. 相似文献
4.
Zhigang Zhu Arunabhiram Chutia Hideyuki Tsuboi Nozomu Hatakeyama Hiromitsu Takaba Momoji Kubo 《Journal of Physics and Chemistry of Solids》2009,70(9):1248-258
A theoretical study on Ru-doped rutile SnO2(1 1 0) surface has been carried out by means of periodic density functional theory (DFT) at generalized gradient approximation (GGA-RPBE) level with a periodic supercell approach. Electronic structure analysis was performed based on the band structure and partial density of states. The results provide evidence that the electronic structures of SnO2(1 1 0) surface are modified by the surface Ru dopant, in which Ru 4d orbital are located at the edge of the band gap region. It is demonstrated that molecular oxygen adsorption characteristics on stoichiometric SnO2(1 1 0) surface are changed from endothermic to exothermic due to the existence of surface Ru dopant. The dissociative adsorption of molecular oxygen on the Ru5c/SnO2(1 1 0) surface is exothermic, which indicates that Ru could act as an active site to increase the oxygen atom species on SnO2(1 1 0) surface. Our present study reveals that the Ru dopant on surface is playing both electronic and chemical role in promoting the SnO2 gas-sensing property. 相似文献
5.
Xiao-Hong Xu Xiao-Hua Shen Xiao-Li Li Fang Wang Feng-Xian Jiang Hai-Shun Wu 《Applied Surface Science》2007,253(7):3382-3386
The L10 CoPt films with (0 0 1) preferred orientation are achieved by fabricating on the glass substrates and post annealing at 600° C for 30 min. The preferred orientation of [ZrO2/CoPt]n/Ag films dependence of the Ag underlayer thickness, ZrO2 and CoPt interlayer thickness is investigated. A large perpendicular magnetic anisotropy and a nearly perfect L10 CoPt (0 0 1) texture are obtained in the [ZrO2 (3 nm)/CoPt (5 nm)]3/Ag (10 nm) film. The existence of ZrO2 plays an important role in reducing the intergranular interactions and in determining the size of CoPt grains. Magnetic reversal in textured CoPt films are close to a Stoner-Wolfarth rotation. 相似文献
6.
Magnetic susceptibility, heat capacity and electrical resistivity measurements have been carried out on a new ruthenate, La2RuO5 (monoclinic, space group P21/c) which reveal that this compound is a magnetic semiconductor with a high magnetic ordering temperature of 170 K. The entropy associated with the magnetic transition is 8.3 J/mol K close to that expected for the low spin (S=1) state of Ru4+ ions. The low temperatures specific heat coefficient γ is found to be nearly zero consistent with the semiconducting nature of the compound. The magnetic ordering temperature of La2RuO5 is comparable to the highest known Curie temperature of another ruthenate, namely, metallic SrRuO3, and in both these compounds the nominal charge state of Ru is 4+. 相似文献
7.
We study dual-synthetic antiferromagnets (DSyAFs) using Co2FeAl (CFA) Heusler electrodes with a stack structure of Ta/CFA/Ru/CFA/Ru/CFA/Ta. When the thicknesses of the two Ru layers are 0.45 nm, 0.65 nm or 0.45 nm, 1.00 nm, the CFA-based DSyAF has a strong antiferromagnetic coupling between adjacent CFA layers at room temperature with a saturation magnetic field of ∼11,000 Oe, a saturation magnetization of ∼710 emu/cm3 and a coercivity of ∼2.0 Oe. Moreover, the DSyAF has a good thermal stability up to 400 °C, at which CFA films show B2-ordered structure. Therefore, the CFA-based DSyAFs are favorable for applications in future spintronic devices. 相似文献
8.
M. Rams A. ZarzyckiA. Pikul K. Tomala 《Journal of magnetism and magnetic materials》2011,323(11):1490-1494
The magnetic properties of R2Ru2O7 pyrochlore compounds (R=Yb, Dy) were studied using specific heat down to 0.4 K and bulk magnetic measurements. These two rare-earth elements were chosen to demonstrate the effect of Ru-R exchange interaction on R magnetic sublattice, in two cases of anisotropy: axial in Dy and planar in Yb. Dy2Ru2O7 undergoes a second order transition to a fully ordered state at 1.85 K with no signs of the spin-ice state. In Yb2Ru2O7 the Yb sublattice orders gradually around 8 K due to the Ru molecular field and no further transition is observed down to 0.4 K. Including the Ru molecular field at the R site in calculations based on crystal field parameters known from titanates R2Ti2O7, allowed us to interpret experimental data. 相似文献
9.
Jun Wan Yunhe Huang Chaoying Ni 《Journal of magnetism and magnetic materials》2010,322(13):1811-10574
Exchange coupling between hard and soft magnetic materials has implications for both permanent magnet and magnetic recording technologies. This paper looks at exchange coupling of FCC FePt epitaxially grown onto (0 0 1) oriented L10 FePt deposited on (0 0 1) MgO substrates at elevated temperature. By varying the thickness of the FCC layer there is a relaxation of the single crystal FCC layer that produces a polycrystalline microstructure as evidenced by the development of rings in the electron diffraction pattern. A concurrent decoupling of the layers is apparent from magnetization curves with two distinct switching fields as the FCC layer thickness is increased above 20 nm. The results shown here confirm the importance of the epitaxial relationship between materials of disparate anisotropies in maintaining strong exchange coupling. 相似文献
10.
M.F. Gerard N.M.C. Casado M. Perec R. Calvo 《Journal of Physics and Chemistry of Solids》2007,68(8):1533-1539
Magnetic and EPR data have been collected for complex [Cu(L-Arg)2](NO3)2·3H2O (Arg=arginine). Magnetic susceptibility χ in the temperature range 2-160 K, and a magnetization isotherm at T=2.29(1) K with magnetic fields between 0 and 9 T were measured. The observed variation of χT with T indicates predominant antiferromagnetic interactions between Cu(II) ions coupled in 1D chains along the b axis. Fitting a molecular field model to the susceptibility data allows to evaluate g=2.10(1) for the average g-factor and J=−0.42(6) cm−1 for the nearest neighbor exchange coupling (defined as Hex=-∑JijSi·Sj). This coupling is assigned to syn-anti equatorial-apical carboxylate bridges connecting Cu(II) ion neighbors at 5.682 Å, with a total bond length of 6.989 Å and is consistent with the magnetization isotherm results. It is discussed and compared with couplings observed in other compounds with similar exchange bridges. EPR spectra at 9.77 were obtained in powder samples and at 9.77 and at 34.1 GHz in the three orthogonal planes of single crystals. At both microwave frequencies, and for all magnetic field orientations a single signal arising from the collapse due to exchange interaction of resonances corresponding to two rotated Cu(II) sites is observed. From the EPR results the molecular g-tensors corresponding to the two copper sites in the unit cell were evaluated, allowing an estimated lower limit |J |>0.1 cm−1 for the exchange interaction between Cu(II) neighbors, consistent with the magnetic measurements. The observed angular variation of the line width is attributed to dipolar coupling between Cu(II) ions in the lattice. 相似文献
11.
T. Matsuu A. Hashimoto H. Fujiura S. Matsunuma T. Inoue T. Doi S. Nakagawa 《Journal of magnetism and magnetic materials》2008
Ru/CoPtCr-SiO2 bilayer prepared at 4 and 26 mTorr of Ar gas pressure for the deposition of Ru and CoPtCr-SiO2 layers, respectively, exhibits better magnetic properties suitable for perpendicular magnetic recording media when they are deposited at room temperature on a Pt seed layer prepared at 450 °C. The Ru-O seed layer fabricated by a reactive sputtering method improves the Ru (0 0 1) texture deposited on a Ru-O layer. The Ru-O/Ru hybrid type of underlayer causes the improvement of the c-axis orientation of CoPtCr crystallites in the CoPtCr-SiO2 layer deposited on it. Fine granulation of magnetic grains in the CoPtCr-SiO2 layer is also attained when they are deposited on the Aramid type of flexible tape substrates. 相似文献
12.
X.F. Hu 《Applied Surface Science》2006,252(13):4625-4627
The synthetic antiferromagnets (SAF) have been used in spin-valve sensor in data storage industry [1]. We report a new hard/Ru/soft sandwich structure (SHBL) fabricated by pulsed lased deposition to replace current single layer structure for information recording application. SHBL consists of two magnetic layers separated by thin nonmagnetic layers, typically with Ru layers of 0.7-1.2 nm, through which antiferromagnetic coupling is induced. Varying the relative thickness of the magnetic layers, the spacer layers, and the type of magnetic materials can alter magnetic properties of CoCrPt/Ru/CoFe superlattice. The coercivity Hc and grain size of magnetic layer is also dependent on the laser fluence. High laser fluence results in both small grain size and high Hc. The observed phenomena are related to high quenching and deposition rates during PLD at high fluence, resulting in more pronounced phase segregation. 相似文献
13.
The magnetic domain structures of Fe78.8−xCoxCu0.6Nb2.6Si9B9 (x=0, 20, 40, 60) alloys are investigated by Lorentz microscopy coupled with the focused ion beam method. The specimen prepared using the FIB method is found to have a considerably more uniform thickness compared to that prepared using the ion-milling method. In Fe38.8Co40Cu0.6Nb2.6Si9B9 and Fe18.8Co60Cu0.6Nb2.6Si9B9 alloys, 180° domain walls extending in the direction of the induced magnetic anisotropy are observed. Analysis with Lorentz microscopy reveals that the width of the magnetic domains decreases with an increase in the cobalt content or the induced magnetic anisotropy Ku, that is, the domain width d is proportional to the induced magnetic anisotropy (Ku)−1/4. On the other hand, in the in situ Lorentz microscopy observation as a function of temperature, magnetic ripple structures are found to appear in a localized area due to the fluctuation of magnetization vectors from 423 K. It is observed that the induced magnetic anisotropy caused by the applied magnetic field at 803 K is not suppressed by the magnetic ripple structures observed at 423–443 K. 相似文献
14.
In this paper, we have performed ab initio density functional theory calculations to compare the miscibility and magnetic properties of two-dimensional binary surface alloys of the form MxN1−x (M = Fe or Co; N = Pt, Au, Ag, Cd or Pb) on two different substrates - Rh(1 1 1) and Ru(0 0 0 1). The trends in miscibility for the two substrates are found to be strikingly similar. The magnetic moments show qualitatively similar behavior, but their magnitudes differ: surface alloys on Rh(1 1 1) have larger magnetic moments than on Ru(0 0 0 1). We infer that strain plays the determining role in stabilizing these two-dimensional alloys, whereas the differences in magnetic moments can be ultimately attributed to the different number of d-electrons in Rh and Ru. 相似文献
15.
The multilayer of Ta/NiFeMo/Ru/Co3Pt was sputter deposited on the Si (1 0 0) wafer. Using the NiFeMo buffer layer greatly enhanced the texture of Co3Pt layer. The enhanced texture increased the perpendicular magnetic anisotropy of Co3Pt. According to the VSM and XRD results, only the 5 nm of NiFeMo was good enough to produce the texture and perpendicular anisotropy in Co3Pt layer. The perpendicular anisotropy was attributed to the existence of short-range-ordered HCP structure of Co3Pt. 相似文献
16.
Core/shell nanoparticles consisting of a magnetic core of zinc-substituted manganese ferrite (Mn0.4Zn0.6Fe2O4) and a shell of silica (SiO2) are prepared by a sol-gel method using tetraethyl orthosilicate (TEOS) as a precursor material for silica and salts of iron, manganese and zinc as the precursor of the ferrite. Three weight percentages of the shell materials of SiO2 are used to prepare the coated nanoparticles. The X-ray diffractograms (XRD) of the coated and uncoated magnetic nanoparticles confirmed that the magnetic nanoparticles are in their mixed spinel phase in an amorphous matrix of silica. Particles sizes of the samples annealed at different temperatures are estimated from the width of the (3 1 1) line of the XRD pattern using the Debye-Sherrer equation. The information regarding the crystallographic structure together with the particles sizes extracted from the high-resolution transmission electron microscopy (HRTEM) of a few selected samples are in agreement with those obtained from the XRD. HRTEM observations revealed that particles are coated with silica. The calculated thickness is in agreement with that obtained from the HRTEM pictures. Hysteresis loops observed in the temperature range 300 down to 5 K and Mössbauer spectra at room temperature indicate superparamagnetic relaxation of the nanoparticles. 相似文献
17.
Investigation on the magnetocaloric effect in DyNi2, DyAl2 and Tb1−nGdnAl2 (n=0, 0.4, 0.6) compounds
V.S.R. de Sousa E.J.R. Plaza B.P. Alho S. Gama P.J. von Ranke 《Journal of magnetism and magnetic materials》2009,321(20):3462-3465
The magnetocaloric effect (MCE) in the DyNi2, DyAl2 and Tb1−nGdnAl2 (n=0, 0.4, 0.6) was theoretically investigated in this work. The DyNi2 and DyAl2 compounds are described considering a model Hamiltonian which includes the crystalline electrical field anisotropy. The anisotropic MCE was calculated changing the magnetic field direction from 〈1 1 1〉 to 〈0 0 1〉 in DyNi2 and from 〈1 0 0〉 to 〈0 1 1〉 in DyAl2. The influence of the second- and first-order spin-reorientation phase transitions on the MCE that occurs in these systems is discussed. For the calculations of the MCE thermodynamic quantities in the Tb1−nGdnAl2 systems we take into account a two sites magnetic model, and good agreement with the available experimental data was obtained. 相似文献
18.
Toshiyuki Taniuchi Hiroshi Kumigashira Masato Kubota Takanori Wakita Takanori Yokoya Kanta Ono Masaharu Oshima Mikk Lippmaa Hideomi Koinuma 《Surface science》2007,601(20):4690-4693
We have used photoelectron emission microscopy (PEEM) and X-ray magnetic circular dichroism (XMCD) to study the effect of thin film thickness on the magnetic domain formation in La0.6Sr0.4MnO3 samples that were epitaxially grown on stepped SrTiO3 (0 0 1) substrates. The magnetic image exhibited a stripe structure elongated along the step direction, irrespective of film thickness, suggesting that uniaxial magnetic anisotropy induced by step-and-terrace structures plays an important role in the magnetic domain formation. Additional domains evolved gradually with increasing film thickness. In these domains, the direction of magnetization differed from the step direction due to biaxial magneto-crystalline anisotropy. The evolution of additional magnetic domains with increasing film thickness implies that a competition exists between the two anisotropies in LSMO films. 相似文献
19.
Vladimir Krivoruchko Tat’yana KonstantinovaAnton Mazur Andrey ProkhorovVictor Varyukhin 《Journal of magnetism and magnetic materials》2006
Using a co-precipitation method, perovskite-type manganese oxide La0.7Sr0.3MnO3 nanoparticles (NPs) with particle size 12 nm were prepared. Detailed studies of both 55Mn nuclear magnetic resonance and superparamagnetic resonance spectrum, completed by magnetic measurements, have been performed to obtain microscopic information on the local magnetic structure of the NP. Our results on nuclear dynamics provide direct evidence of formation of a magnetically dead layer, of the thickness ≈2 nm, at the particle surface. Temperature dependences of the magnetic resonance spectra have been measured to obtain information about complex magnetic properties of La0.7Sr0.3MnO3 fine-particle ensembles. In particular, electron paramagnetic resonance spectrum at 300 K shows a relatively narrow sharp line, but as the temperature decreases to 5 K, the apparent resonance field decreases and the line width considerably increases. The low-temperature blocking of the NPs magnetic moments has been clearly observed in the electron paramagnetic resonances. The blocking temperature depends on the measuring frequency and for the ensemble of 12 nm NPs at 9.244 GHz has been evaluated as 110 K. 相似文献
20.
J.A.H. Coaquira L.B. Carvalho A.W. Carbonari S. Quezado 《Physica B: Condensed Matter》2009,404(19):3116-3118
Structural, magnetic and hyperfine interaction measurements have been carried out on the novel compound La3.5Ru4O13 prepared under two different atmospheres (air and oxygen flow). This compound is formed in the orthorhombic structure (space group Pmmm, # 47). The coexistence of the triple-layered perovskite-type planes (quasi-2D structure) and the rutile-like slabs (1D structure) leads to interesting magnetic and electronic properties in this compound. The magnetic susceptibility of this system shows a peak at T~47 K associated with antiferromagnetic interactions. The Curie-Weiss behaviour of the susceptibility provides an effective magnetic moment consistent with Ru ions in low-spin state. Perturbed angular correlation measurements carried out with 111Cd probe in the temperature range 10-60 K reveal only quadrupole interactions and indicate the occurrence of structural distortions for T<40 K. 相似文献