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New types of functional material structures will emerge if the shape and properties are controlled in three-dimensional nanodevices. Possible applications of these would be nanoelectronics and medical systems. Magnetic nanoparticles (MNPs) are especially important in electronics such as magnetic storage, sensors, and spintronics. Also, in those that are used as magnetic resonance imaging contrasts, and tissue specific therapeutic agents, as well as in the labeling and sorting of cells, drug delivery, separation of biochemical products, and in other medical applications. Most of these applications require MNPs to be chemically stable, uniform in size, and controllable in terms of their magnetic properties and shape. In this paper three new functions of iron (Fe)-based nanoparticles are reported: shape transformation, oxidation prevention, and self-alignment. The shape of the Fe nanoparticles could be controlled by changing their oxidation states and properties by using a nanocarbon coating. Full field X-ray microscopy using synchrotron radiation revealed controllable magnetic properties of MNPs at the L3 edge which depended on the oxidation states. Then, inkjet printing was successfully performed to deposit a uniform layer of MNPs by the size.

Nanomagnetic devices in -The sub-5-nm size range still do not exist, not only because of many fabrication and characterization challenges but also because of -The poorly understood physics in this size range. Previous experimental studies from various groups have shown that -The spin relaxation time can be increased by orders of magnitude with this size reduction. The increased spin lifetime leads to a combination of effects such as spin accumulation and tunneling magnetoresistance enhancement which in turn can significantly and favorably affect -The device performance [1]. The goal of this study is to exploit this new physics through fabrication and testing of magnetic tunneling junction (MTJ) devices with a characteristic size of below 5 nm. To achieve this goal, we integrate magnetic nanoparticles into MTJ structures and measure -Their key properties such as I-V curves and magnetoresistance dependencies. The nanoparticles, with sizes ranging from below 2 to over 10 nm, are made of -The ferrimagnetic spinel ferrite CoFe2O4 using co-precipitation chemistry. It has been -Theoretically predicted that -These nanoparticles become half-metallic in this size range and thus can lead to unprecedented high magnetoresistance values. Indeed, -The nanodevices under study display spin-filtering properties, as confirmed through measurements of magnetoresistance and I-V dependences [2]. This paper summarizes -The measured room-temperature anomalous magnetoresistance and I-V curves with a Coulomb-staircase-like dependence characteristic of a single-electron transport.

The spin-transfer torque magnetic tunneling junction (MTJ) technology may pave a way to a universal memory paradigm. MTJ devices with perpendicular magnetic anisotropy have the potential to have high thermal stability, high tunneling magnetoresistance, and low critical current for energy-efficient current-induced magnetization switching. Using devices fabricated through focused ion beam etching with Ga-and Ne-ion beams, this paper aimed to understand the size dependence of the current/voltage characteristics in the sub-10 nm range. The switching current density drastically dropped around 1 MA/cm2 as the device size was reduced below 10 nm. A stability of over 22 kT measured for a 5 nm device indicated a significantly reduced spin relaxation time.

Unlike any other nanoparticles known to date, magnetoelectric nanoparticles (MENPs) can generate relatively strong electric fields locally via the application of magnetic fields and, vice versa, have their magnetization change in response to an electric field from the microenvironment. Hence, MENPs can serve as a wireless two‐way interface between man‐made devices and physiological systems at the molecular level. With the recent development of room‐temperature biocompatible MENPs, a number of novel potential medical applications have emerged. These applications include wireless brain stimulation and mapping/recording of neural activity in real‐time, targeted delivery across the blood–brain barrier (BBB), tissue regeneration, high‐specificity cancer cures, molecular‐level rapid diagnostics, and others. Several independent in vivo studies, using mice and nonhuman primates models, demonstrated the capability to deliver MENPs in the brain across the BBB via intravenous injection or, alternatively, bypassing the BBB via intranasal inhalation of the nanoparticles. Wireless deep brain stimulation with MENPs was demonstrated both in vitro and in vivo in different rodents models by several independent groups. High‐specificity cancer treatment methods as well as tissue regeneration approaches with MENPs were proposed and demonstrated in in vitro models. A number of in vitro and in vivo studies were dedicated to understand the underlying mechanisms of MENPs‐based high‐specificity targeted drug delivery via application of d.c. and a.c. magnetic fields. This article is categorized under:Nanotechnology Approaches to Biology > Nanoscale Systems in BiologyTherapeutic Approaches and Drug Discovery > Nanomedicine for Neurological DiseaseTherapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic DiseaseTherapeutic Approaches and Drug Discovery > Emerging Technologies [ABSTRACT FROM AUTHOR]

The objective of this research is to calculate the minimum parameters required to make low-field low-size nano nuclear magnetic resonance (NanoNMR) a viable technology and potentially one of the future Lab-On-Chip technologies. By low field we signify an externally applied magnetic field of less than 0.5 T, and by low size we mean a magnet whose largest physical dimension does not exceed 25 mm. The goal is to develop small and cost-effective NMR spectrometers that can be used at room temperature in a small office environment. In this paper, tunneling magneto resistance (TMR) devices are used to sense the NMR signal. The parameters that are calculated are: minimum sample size and concentration required to obtain an adequate NMR signal, TMR sensor size, and its distance to the sample, RF coil size, RF frequency, and power. The nanoscale TMR sensors proposed in this paper were designed using an in-house developed software tool. The optimally calculated TMR sensors have [Fe.sub.50] [Co.sub.50] PL and FL layers, an area of 100 nm x 100 nm, a 0.3-nm-thick [Al.sub.2][O.sub.3] barrier and is biased at 200 mV. Index Terms--Nuclear magnetic resonance (NMR), giant magneto-resistance (GMR), tunneling magneto resistance (TMR), nano(NMR), lab-on-chip.

Today, conventional magnetic recording schemes are coming to an end because of the superparamagnetic limit. Heat-assisted magnetic recording (HAMR) may ultimately extend data densities beyond 1 TB/[in.sup.2]. HAMR systems utilize the phenomenon during which the magnetic properties of the recording media could be locally modified via heating (optionally, by an optical source in the near field) to temperature in the vicinity of the Curie value of the media material. As a result, heat induced by the optical source can temporarily reduce the magnetic coercivity of high anisotropy material to a level attainable by the magnetic writing head, thus making it feasible to record on relatively small ultra-high anisotropy (and thermally stable) grains, consequently enhancing the a real density dramatically. The key challenge is to develop a near-field transducer capable of delivering over 50 nW into a spot diameter of 30 nm. Traditional fiber schemes are barely capable of 0.1 nW. To resolve the issue, a laser diode could be placed with the emitting edge only a few nanometers away from the recording media. The light can propagate through a nanoaperture on the surface of an aluminum-coated emitting edge. This paper will present an experimental study of recording characteristics of various near-field transducers fabricated via focused ion beam (FIB). To count the number of photons emitted in the near field, a scanning near-field optical microscopy system has been implemented. The experiments indicate that the FIB-fabricated transducers could deliver power of over a few microwatt into a 30-nm spot (Fig. 7). Index Terms--Focused ion beam, heat-assisted magnetic recording (HAMR), scanning near-field optical microscopy.

The playback characteristics of common magnetoresistive heads applied in magnetic recording systems are examined based on bit-patterned medium. The results reveal that analytical solution for a pointlike reader is used to elucidate the playback resolution limits for given patterned medium morphology.

The selected aspects of the recording physics of magnetic data storage specific to writing and reading in patterned medium are discussed. The influence of a recording layer design on playback resolution is evaluated, which offers guidelines for the design and optimization of patterned magnetic recording medium.

The magnetization dynamics of soft underlayers (SULs) within perpendicular magnetic recording media were examined with the help of time-resolved Kerr imaging. The film switching speeds were found to be similar to the switching speed of the driving head for both longitudinal and perpendicular heads in the SUL films without media.

Cobalt ferrite Co[Fe.sub.2][O.sub.4] crystalline nanoparticles (50-100 nm) were produced by carbon combustion synthesis of oxides (CCSO). In this combustion synthesis process, the exothermic oxidation of carbon generates a thermal reaction wave that propagates through the solid reactants mixture of CoO and [Fe.sub.2][O.sub.3] converting it to cobalt ferrite. The extensive emission of C[O.sub.2] increased the porosity and friability of the product. The quenching front method combined with XRD and VSM characterization revealed that crystalline Co[Fe.sub.2][O.sub.4] particles formed in the early stage of the combustion, before the temperature reached its maximum. The maximum value of the coercivity of the quenched product within the front region was 940 Oe with a magnetization of 15 emu/g. The as-synthesized ferrites had hard magnetic properties with coercivity of 700 Oe and saturation magnetization of up to 47 emu/g. Index Terms--Carbon combustion, cobalt ferrites, nanostructured materials.