http://files.janapv.webnode.cz/200000097-8a03f8afdf/ex_bias_nano.pdf

Exchange bias in nanostructures

Magnetocaloric effect: From materials research to refrigeration devices

Magnetic Heusler alloys which undergo a martensitic transition display interesting functional properties. In the present review, we survey the magnetocaloric effects of Ni-Mn-based Heusler alloys and discuss their relation with the magnetic shape-memory and magnetic superelasticity reported in these materials. We show that all these effects are a consequence of a strong coupling between structure and magnetism which enables a magnetic field to rearrange martensitic variants as well as to provide the possibility to induce the martensitic transition. These two features are respectively controlled by the magnetic anisotropy of the martensitic phase and by the difference in magnetic moments between the structural phases. The relevance of each of these contributions to the magnetocaloric properties is analysed.

https://iopscience.iop.org/article/10.1088/0953-8984/21/23/233201/pdf

Magnetocaloric effect and its relation to shape-memory properties in ferromagnetic Heusler alloys

We analyze theoretically the optical properties of ideal semiconductor crystallites so small that they show quantum confinement in all three dimensions [quantum dots (QD's)]. In the limit of a QD much smaller than the bulk exciton size, the linear spectrum will be a series of lines, and we consider the phonon broadening of these lines. The lowest interband transition will saturate like a two-level system, without exchange and Coulomb screening. Depending on the broadening, the absorption and the changes in absorption and refractive index resulting from saturation can become very large, and the local-field effects can become so strong as to give optical bistability without external feedback. The small QD limit is more readily achieved with narrow-band-gap semiconductors.

Theory of the linear and nonlinear optical properties of semiconductor microcrystallites

In order to study the effects of iron oxide (IO) nanoparticles on Staphylococcus aureus, IO nanoparticles were synthesized via a novel matrix-mediated method using polyvinyl alcohol (PVA). The IO nanoparticles were characterized by transmission electron microscopy and dynamic light scattering. Further, S. aureus were grown in the presence of three different IO nanoparticle concentrations for four, 12, and 24 hours. Live/dead assays were performed and the results provide evidence that IO/PVA nanoparticles inhibited S. aureus growth at the highest concentration (3 mg/mL) at all time points.

/pdf/bactericidal-effect-of-iron-oxide-nanoparticles-on-gnrk4o0y6u.pdf

Bactericidal effect of iron oxide nanoparticles on Staphylococcus aureus

Effect of annealing on the martensitic transformation of a CoNiAl ferromagnetic shape memory alloy

The magnetic ground state of the Mn50Ni38.5Sn11.5 alloy is investigated through dc/ac magnetization and low-temperature specific-heat measurements. The dc and ac magnetization measurements indicate that the system can be identified as a cluster spin glass (CSG) phase in a ferromagnetic (FM) background, and as a conjunction of these two phases an exchange bias effect (EBE) is observed in this system. The presence of coexisting phases is further supported by our measurement. We attribute the existence of the CSG phase to the antiferromagnetic (AFM) interaction arising from the Mn-Mn antisite disorder which further enhances through martensite transformation. The anomalous increase of C p below 0.7 K is due to the nuclear Schottky anomaly arising from the hyperfine splitting of the nuclear levels of Mn atoms. Detailed reasons for the observed behaviours are discussed in the paper.

http://iopscience.iop.org/article/10.1209/0295-5075/109/47006/pdf

Origin of cluster spin glass and nuclear Schottky anomaly in Mn50Ni38.5Sn11.5 alloy

A novel route has been developed to synthesize polyaniline (PANI)/nickel oxide (NiO) nanocomposites via liquid/liquid interfacial polymerization where NiO and the initiator were dispersed in the aqueous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet−visible absorption, X-ray diffraction, and electrochemical, electrical conductivity and magnetic property measurements. NiO was dispersed uniformly within the PANI matrix. The composites exhibited noticeable improvement in thermal stability and electrical conductivity in comparison with pure PANI. The composites showed excellent electrochemical reversibility at a scan rate of 0.1 V s−1 and good redox stability even up to 100 cycles. The room temperature magnetic hysteresis measurements show a low value of coercivity for the polymer composites in comparison with NiO. The remnant magnetization (Mr) values were found to be increased with increasing concentration of NiO in the composites. © 2013 Society of Chemical Industry

Preparation of polyaniline/nickel oxide nanocomposites by liquid/liquid interfacial polymerization and evaluation of their electrical, electrochemical and magnetic properties

Ultra-thin MoO3 films were deposited onto glass and Si substrates by r.f. magnetron sputtering. The optical and IR properties of the films were studied in the range of 250 to 1000 nm and 400 to 1500 cm−1, respectively. The optical transmission spectra show a significant shift in absorption edge. The energy gap of the films deposited at 373 K and 0.1 mbar was found to be 3.93 eV, and it decreases with increasing substrate temperature and decreasing sputtering pressure. The IR transmittance spectra shows strong modes of vibrations of Mo=O and Mo–O–Mo units of MoO3 molecule. A significant change in energy gap and a shift in frequency of IR modes were observed in ultra-thin MoO3 films.

Optical and IR studies on r.f. magnetron sputtered ultra-thin MoO3 films

Yielding behavior and temperature-induced on-field oscillatory rheological studies in a novel MR suspension containing polymer-capped Fe3Ni alloy microspheres

P. K. Mukhopadhyay

Papers

Effect of annealing on the martensitic transformation of a CoNiAl ferromagnetic shape memory alloy

Origin of cluster spin glass and nuclear Schottky anomaly in Mn50Ni38.5Sn11.5 alloy

Preparation of polyaniline/nickel oxide nanocomposites by liquid/liquid interfacial polymerization and evaluation of their electrical, electrochemical and magnetic properties

Optical and IR studies on r.f. magnetron sputtered ultra-thin MoO3 films

Yielding behavior and temperature-induced on-field oscillatory rheological studies in a novel MR suspension containing polymer-capped Fe3Ni alloy microspheres