Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

We have applied a scanning HTS (high-temperature superconductor) de SQUID (superconducting quantum interference device) -based magnetic microscope to study the magnetic properties of Au/Ni/Si(100) films in the thickness range from 8 to 200 Angstrom at T = 77 K. A one-domain structure with in-plane orientation of the magnetic moment was found for film thicknesses exceeding 26 Angstrom. A drastic decrease of the magnetization of the film was detected when the thickness is less than 26 Angstrom

Structure and magnetocaloric properties of La1-xKxMnO3 manganites

A technology of obtaining the single-phase ceramic samples of La1-xKxMnO3 manganites and the dependence of their structural parameters on the content of potassium has been described. Magnetocaloric effect (MCE) in the obtained samples has been measured by two independent methods: by classical direct methodic and by a method of magnetic field modulation. The values of MCE obtained by both methods have been substantially differed. The explanation of the observed divergences is given. The correlation between the level of doping and MCE value has been defined. The value of TC determined by the MCE maximum has been conformed to the literature data received by other methods.Comment: 14 pages, 6 figures, 3 table

Frequency dependence of magnetothermal properties for magnetic fluid and magnetically functionalized implants

Heating of the magnetic nanoparticles in AC magnetic field is the effect promising for application in medicine. The mechanisms of heating in AC-magnetic field implies nontrivial dependence of the power dissipated by magnetic nanoparticles on frequency. With the use of a reconfigurable experimental setup, this frequency-dependent magnetic heating was measured on two characteristic examples: the magnetite nanoparticles conventionally used in medicine and polymer coating with micrometer sized magnetite particles. The saturation of the heating power with frequency is shown that is more pronounced for the second case of microparticles

Young's Modulus and Internal Friction of Yttrium

A detailed study of the temperature dependence of Young's modulus $E(T)$ and internal friction $Q^{-1}(T)$ has been made for various purity single crystals and polycrystalline samples of yttrium. Measurements have been carried out in the temperature range $4.2-400$ K at frequencies $f\sim 1$ kHz. It was found that $E_{\rm bp}=134$ GPa and $E_{\rm c}=51$ GPa at $T=4.2$ K in the basal plane and along the $c$-axis, respectively. It was established that the $E(T)$ curves for single crystals have a Debye-like shape in the temperature interval $4.2-320$ K (the Debye temperature $\Theta_{\rm D}=135$ K and $\Theta_{\rm D}=98$ K in the case of basal plane and the $c$-axis, respectively. $Q^{-1}(T)$ at a temperature near 400 K displays maxima connected with relaxation processes of defects and dislocations in the samples