B. Barbara

Bio: B. Barbara is an academic researcher. The author has contributed to research in topics: Particle & Magnetometer. The author has an hindex of 1, co-authored 2 publications receiving 15 citations.

Novel Magnetic Structures and Nanostructures

Abstract: An overview of new fields of investigation of novel magnetic structures is presented. These structures going from nanometer to micron scales are generally made of ferromagnetic particles deposited on normal or superconducting films, or of multilayer structures. They are studied by conventional SQUID magnetometry (ensemble or array of particles) or near-field techniques (single particle measurements).

Ferrite Materials: Nano to Spintronics Regime

Abstract: For past decade the development of magnetic materials particularly, ferrites in nano form has undergone a fast expanding evolutionary growth as strategic material in spintronics and sensor applications. In this chapter a brief introduction about the importance and need of bulk and nanoferrite, their applications in various fields like in communication, microwave, electromagnetic shielding, memory devices, multiferroics, spintronics devices, humidity/gas sensing, drug delivery, hyperthermia, biosensors, and so on, have been elaborated. Broadly chapter precisely discusses fabrication techniques, magnetic and electrical properties along with application of ferrite nanostructures or nanomaterials. It also includes fundamental understanding of the subject relating physical properties or phenomenon with material dimension. An effort has been made to describe two-dimensional nanostructures: thin films of ferrite with a cursory look on basic explanation of spintronics future applications. Gas/humidity sensing mechanism of ferrite and its application at nanoscale has been outlined related to recent advancements. A special care has been taken to include necessary theoretical background and experimental details for different techniques employed for the synthesis of ferrite nanoparticles, ferrite composites, and two-dimensional nanostructures—thin film materials. In totality chapter has been interlaced with a lucid introduction on the fundamentals and typical experimental approaches of few well-established techniques of nanoparticle synthesis particularly used for ferrites.

Formation of ordered CoAl alloy clusters by the plasma-gas condensation technique

Abstract: CoxAl1−x alloy clusters were synthesized from a mixture of Co and Al metal vapors generated by the sputtering of pure metal targets. We observed that the produced alloy clusters were uniform in size, ranging from approximately 20 nm for Al-rich clusters to 10 nm for Co-rich clusters. For a wide average composition range (x≈0.4–0.7), the alloy clusters have the ordered B2 (CsCl-type) structure. In the Co-rich cluster aggregates (x=0.76), the clusters are composed of face-centered-cubic (fcc) Co and minor CoAl(B2) clusters. In the Al-rich aggregates (x=0.23), the clusters are mainly composed of the fcc-Al phase, although clusters occasionally possess a “core-shell structure” with the CoAl(B2) phase surrounded by an Al-rich amorphous phase. These observations are in general agreement with our prediction based on the equilibrium phase diagram. We also noticed that the average composition depends not only on the relative amount of Co and Al vapors, but also on their absolute amount, and even on the Ar gas flow...

Time-of-flight high-mass spectrometer observation of large size Nb clusters toward assembling of size controlled clusters

Abstract: Using a plasma-gas-condensation-type cluster source, we could obtain nano-scale clusters with the average diameter between 2 and 13 nm. In order to detect such large free clusters containing 1–105 atoms, we have constructed a time-of-flight high-mass spectrometer (TOF-HMS). The size distribution of the Nbn clusters observed by the TOF-HMS is in good agreement with the result of the transmission electron microscope observation. The mass spectra have been measured with varying the operational parameters of the cluster source. They are shifted to the smaller size direction and the mass distribution becomes narrower with increasing the He gas flow rate, VHe, and keeping the Ar gas flow rate, VAr, constant. These features are attributable to the decrease in the residence times of gaseous species in the cluster source. The cluster size increases with increasing the Ar gas pressure and lowering the temperature of the cluster source.