scholarly journals Structure, morphology, and magnetic properties of Fe nanoparticles deposited onto single-crystalline surfaces

2011 ◽  
Vol 2 ◽  
pp. 47-56 ◽  
Author(s):  
Armin Kleibert ◽  
Wolfgang Rosellen ◽  
Mathias Getzlaff ◽  
Joachim Bansmann
Keyword(s):  
Magnetic Properties ◽  
Structural Properties ◽  
Critical Size ◽  
Magnetic Nanostructures ◽  
High Energy ◽  
Particle Orientation ◽  
Spin Orbital ◽  
Single Crystalline ◽  
Dependent Relation ◽  
Fe Nanoparticles

Background: Magnetic nanostructures and nanoparticles often show novel magnetic phenomena not known from the respective bulk materials. In the past, several methods to prepare such structures have been developed – ranging from wet chemistry-based to physical-based methods such as self-organization or cluster growth. The preparation method has a significant influence on the resulting properties of the generated nanostructures. Taking chemical approaches, this influence may arise from the chemical environment, reaction kinetics and the preparation route. Taking physical approaches, the thermodynamics and the kinetics of the growth mode or – when depositing preformed clusters/nanoparticles on a surface – the landing kinetics and subsequent relaxation processes have a strong impact and thus need to be considered when attempting to control magnetic and structural properties of supported clusters or nanoparticles. Results: In this contribution we focus on mass-filtered Fe nanoparticles in a size range from 4 nm to 10 nm that are generated in a cluster source and subsequently deposited onto two single crystalline substrates: fcc Ni(111)/W(110) and bcc W(110). We use a combined approach of X-ray magnetic circular dichroism (XMCD), reflection high energy electron diffraction (RHEED) and scanning tunneling microscopy (STM) to shed light on the complex and size-dependent relation between magnetic properties, crystallographic structure, orientation and morphology. In particular XMCD reveals that Fe particles on Ni(111)/W(110) have a significantly lower (higher) magnetic spin (orbital) moment compared to bulk iron. The reduced spin moments are attributed to the random particle orientation being confirmed by RHEED together with a competition of magnetic exchange energy at the interface and magnetic anisotropy energy in the particles. The RHEED data also show that the Fe particles on W(110) – despite of the large lattice mismatch between iron and tungsten – are not strained. Thus, strain is most likely not the origin of the enhanced orbital moments as supposed before. Moreover, RHEED uncovers the existence of a spontaneous process for epitaxial alignment of particles below a critical size of about 4 nm. STM basically confirms the shape conservation of the larger particles but shows first indications for an unexpected reshaping occurring at the onset of self-alignment. Conclusion: The magnetic and structural properties of nanoparticles are strongly affected by the deposition kinetics even when soft landing conditions are provided. The orientation of the deposited particles and thus their interface with the substrate strongly depend on the particle size with consequences regarding particularly the magnetic behavior. Spontaneous and epitaxial self-alignment can occur below a certain critical size. This may enable the obtainment of samples with controlled, uniform interfaces and crystallographic orientations even in a random deposition process. However, such a reorientation process might be accompanied by a complex reshaping of the particles.

Rare earth permanent magnetic nanostructures: chemical design and microstructure control to optimize magnetic properties

2021 ◽  
Author(s):  
Junjie Xu ◽  
Kai Zhu ◽  
Song Gao ◽  
Yanglong Hou
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Exchange Coupling ◽  
Magnetic Nanostructures ◽  
Microstructure Control ◽  
Size And Shape ◽  
Chemical Design

The routes for the optimization of the magnetic properties of rare earth permanent magnetic nanostructures are discussed, i.e. the control of microstructure, such as size and shape as well as the exchange-coupling interactions.

scholarly journals Magnetic properties and crystal structure of elemental cobalt powder modified by high-energy ball milling

2019 ◽  
Vol 8 (5) ◽  
pp. 4995-5003 ◽  
Author(s):  
J.A. Betancourt-Cantera ◽  
F. Sánchez-De Jesús ◽  
A.M. Bolarín-Miró ◽  
G. Torres-Villaseñor ◽  
L.G. Betancourt-Cantera
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Cobalt Powder ◽  
Energy Ball

scholarly journals Magnetic properties of iron nitride-alumina nanocomposite materials prepared by high-energy ball milling

2003 ◽  
Vol 24 (1-3) ◽  
pp. 93-96 ◽  
Author(s):  
S. R. Mishra ◽  
G. J. Long ◽  
F. Grandjean ◽  
R. P. Hermann ◽  
S. Roy ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Ball Milling ◽  
High Energy ◽  
Nanocomposite Materials ◽  
High Energy Ball Milling ◽  
Iron Nitride ◽  
Energy Ball

Line-Shaped Electron Beam System and Soi Films Prepared by The System

1985 ◽  
Vol 45 ◽  
Author(s):  
Y. Hayafuji ◽  
A. Shibata ◽  
T. Yanada ◽  
A. Sawada ◽  
S. Usui ◽  
...  
Keyword(s):  
Electron Beam ◽  
Crystalline Silicon ◽  
Semiconductor Industry ◽  
High Energy ◽  
Silicon Films ◽  
High Energy Density ◽  
Present System ◽  
Single Crystalline ◽  
Beam System ◽  
Scanning Area

ABSTRACTThe line-shaped electron beam annealing system which generates an electron beam of a length of 4 cm and a width af less than 100 um with a high energy density exceeding well over 100 kW/cm2 was developed for the first time with a purpose of SOI processing as its primary application. An pccelaration voltage of up to 20 kV can be used in this system. Seeded single crystalline islands with areas several mm long and 30 to 100 um in width were obtained by a single scan of the electron beam. The electron beam is generated in a pulsed way in the system due to the power restriction of the power supplies. An area of 4×5 cm2 was processed by a single scan of an electron beam at a sample speed of 530 cm/sec and a beam duration of 9.5 msec. The scanning area for one scan is determined by the beam length and the duration of the beam and sample speed.The present system could give single crystalline silicon films without any grain boundaries. The electron mobility of the electron beam recrystallized films, obtained from FETs made as a vehicle to test the electrical properties of the films, was comparable to that of the bulk silicon. A very rapid migration of silicon atoms in solid polycrystalline silicon films, which is controllable by process parameters, was also found with a migration speed of the order of 1 m/sec in a capped structure. The present electron beam system is useful in studying basic mechanisms of crystal growth in thin films. The system can have a very high throughput, a desirable feature in semiconductor industry. The present system can also be used to study the rapid thermal treatment of materials other than semiconductors including rapidly solidified materials.

Effect of Nitridation Magnetic Properties of Nanocrystalline Fe-Co Alloy Powders

2010 ◽  
Vol 654-656 ◽  
pp. 1106-1109
Author(s):  
Ya Qiong He ◽  
Chang Hui Mao ◽  
Jian Yang
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
High Energy ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron ◽  
Nitridation Temperature ◽  
Microstructure And Magnetic Properties

Nanocrystalline Fe-Co alloy powders, which were prepared by high-energy mechanical milling, were nitrided under the mixing gas of NH3/H2 in the temperature range from 380°C to 510°C. X-ray diffraction (XRD) was used to analyze the grain size and reaction during the processing. The magnetic properties of the nitrided powders were measured by Vibrating Sample Magnetometer (VSM). The results show that with the appearance of Fe4N phase after nitride treatment, and the grain-size of FeCo phase decreases with the increase of nitridation temperature between 380°C to 450°C.The saturation magnetization of nitrided alloy powder treated at 480°C is about 18% higher than that of the initial Fe-Co alloy powder, accompanied by the reduction of the coercivity. Transmission electron microscope (TEM) was used, attempting to further analyze the effect of Fe4N phase on microstructure and magnetic properties of the powder mixtures.

Properties of Epitaxial SrTiO3 Thin Films Grown on Silicon by Molecular Beam Epitaxy

1999 ◽  
Vol 567 ◽  
Author(s):  
Z. Yu ◽  
R. Droopad ◽  
J. Ramdani ◽  
J.A. Curless ◽  
C.D. Overgaard ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
High Energy ◽  
State Density ◽  
Unit Cell ◽  
Ex Situ ◽  
Silicon Oxide Layer ◽  
Single Crystalline ◽  
X Ray

ABSTRACTSingle crystalline perovskite oxides such as SrTiO3 (STO) are highly desirable for future generation ULSI applications. Over the past three decades, development of crystalline oxides on silicon has been a great technological challenge as an amorphous silicon oxide layer forms readily on the Si surface when exposed to oxygen preventing the intended oxide heteroepitaxy on Si substrate. Recently, we have successfully grown epitaxial STO thin films on Si(001) surface by using molecular beam epitaxy (MBE) method. Properties of the STO films on Si have been characterized using a variety of techniques including in-situ reflection high energy electron diffraction (RHEED), ex-situ X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Auger electron spectroscopy (AES) and atomic force microscopy (AFM). The STO films grown on Si(001) substrate show bright and streaky RHEED patterns indicating coherent two-dimensional epitaxial oxide film growth with its unit cell rotated 450 with respect to the underlying Si unit cell. RHEED and XRD data confirm the single crystalline nature and (001) orientation of the STO films. An X-ray pole figure indicates the in-plane orientation relationship as STO[100]//Si[110] and STO(001)// Si(001). The STO surface is atomically smooth with AFM rms roughness of 1.2 AÅ. The leakage current density is measured to be in the low 10−9 A/cm2 range at 1 V, after a brief post-growth anneal in O2. An interface state density Dit = 4.6 × 1011 eV−1 cm−2 is inferred from the high-frequency and quasi-static C-V characteristics. The effective oxide thickness for a 200 Å STO film is around 30 Å and is not sensitive to post-growth anneal in O2 at 500-700°C. These STO films are also robust against forming gas anneal. Finally, STO MOSFET structures have been fabricated and tested. An extrinsic carrier mobility value of 66 cm2 V−11 s−1 is obtained for an STO PMOS device with a 2 μm effective gate length.

Magnetic properties of single-crystalline CePt0.75Pd0.25Sn

2004 ◽  
Vol 272-276 ◽  
pp. E117-E118
Author(s):  
B. Janoušová ◽  
V. Sechovský ◽  
A.H. Lacerda ◽  
T. Komatsubara
Keyword(s):  
Magnetic Properties ◽  
Single Crystalline

scholarly journals Probing nanoscale behavior of magnetic materials with soft X-ray spectromicroscopy

2012 ◽  
Vol 1 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Peter Fischer ◽  
Charles S. Fadley
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Spin Dynamics ◽  
Magnetic Nanostructures ◽  
Magnetic Behavior ◽  
Research Area ◽  
X Ray ◽  
Spatially Resolved ◽  
Buried Interfaces ◽  
Analytical Tools

AbstractThe magnetic properties of matter continue to be a vibrant research area driven both by scientific curiosity to unravel the basic physical processes which govern magnetism and the vast and diverse utilization of magnetic materials in current and future devices, e.g., in information and sensor technologies. Relevant length and time scales approach fundamental limits of magnetism and with state-of-the-art synthesis approaches we are able to create and tailor unprecedented properties. Novel analytical tools are required to match these advances and soft X-ray probes are among the most promising ones. Strong and element-specific magnetic X-ray dichroism effects as well as the nanometer wavelength of photons and the availability of fsec short and intense X-ray pulses at upcoming X-ray sources enable unique experimental opportunities for the study of magnetic behavior. This article provides an overview of recent achievements and future perspectives in magnetic soft X-ray spectromicroscopies which permit us to gain spatially resolved insight into the ultrafast spin dynamics and the magnetic properties of buried interfaces of advanced magnetic nanostructures.

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