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

Magnetic field and stress Induced strain in CoNiAl Ferromagnetic Shapememory Alloy

Experimental and theoretical investigations of the stress-induced twinning/detwinning in the martensite phase of a FSMA system

/pdf/dielectric-relaxation-and-charge-transport-process-in-prcro3-4dolspd5zv.pdf

Dielectric relaxation and charge transport process in PrCrO3 nano-ceramic

The nonlinear current voltage characteristics of a point contact convey information about various excitations in the metal. We have made a poin~ contact study on a superconductor to see the band gap and on a normal metal to see Ihe transport
characteristics.

/pdf/superconducting-gap-in-nb-seen-by-point-contact-spectroscopy-l1r64erp4h.pdf

Superconducting gap in Nb seen by point contact spectroscopy

Study o Ferromagnetic shape memory alloys (FSMAs) is an interesting topic of present day research because of their large magnetic field induced shape recovery. They are important materials for the development of sensors and actuator based applications. Attempt for miniaturization of these actuators and sensors have led to the study of thin films. Bulk CoNiAl alloys are promising FSMAs because of their higher ductility and large range of control over the magnetic and structural transformation temperatures. To investigate the physical properties in thin film form we fabricated CoNiAl alloy films by D.C. sputtering method on glass substrates (kept at room temperature) under various conditions. They were annealed in vacuum at 500 0 C for 1h. The samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and ellipsometry. Thickness of the films was found to be lying between 70 and 272 nm. Fine grained microstructure was found for all the deposited films. The transformation temperatures of the samples were taken from the resistivity measurement done between 80 and 350 K. Magnetization measurements were also done between 80 and 400 K by using a vibrating sample magnetometer, but the Curie temperatures of the present films were not found to be below 400 K and magnetoelastic couplings were found to be rather weak.

/pdf/fabrication-and-magnetic-properties-of-conial-ferromagnetic-462bs6ewpv.pdf

P. K. Mukhopadhyay

Papers

Magnetic field and stress Induced strain in CoNiAl Ferromagnetic Shapememory Alloy

Experimental and theoretical investigations of the stress-induced twinning/detwinning in the martensite phase of a FSMA system

Dielectric relaxation and charge transport process in PrCrO3 nano-ceramic

Superconducting gap in Nb seen by point contact spectroscopy

Fabrication and Magnetic Properties of CoNiAl Ferromagnetic Shape memory Alloy thin films