Probing the field-induced variation of the chemical potential in Bi(2)Sr(2)CaCu(2)O(y) via the magneto-thermopower measurements

Approximating the shape of the measured in $Bi_2Sr_2CaCu_2O_y$ magneto-thermopower (TEP) $\Delta S(T,H)$ by asymmetric linear triangle of the form $\Delta S(T,H)\simeq S_p(H)\pm B^{\pm}(H)(T_c-T)$ with positive $B ^{-}(H)$ and $B ^{+}(H)$ defined below and above $T_c$, we observe that $B ^{+}(H)\simeq 2B ^{-}(H)$. In order to account for this asymmetry, we explicitly introduce the field-dependent chemical potential of holes $\mu (H)$ into the Ginzburg-Landau theory and calculate both an average $\Delta S_{av}(T,H)$ and fluctuation $\Delta S_{fl}(T,H)$ contributions to the total magneto-TEP $\Delta S(T,H)$. As a result, we find a rather simple relationship between the field-induced variation of the chemical potential in this material and the above-mentioned magneto-TEP data around $T_c$, viz. $\Delta \mu (H)\propto S_p(H)$.Comment: REVTEX (epsf), 4 pages, 2 PS figures; to be published in JET

EPR study of polycrystalline superconductors with YBa2Cu3O7 structure

Electron paramagnetic resonance (EPR) of Gd3+, Eu2+, and copper ions has been investigated in the high-Tc superconductor with YBa2Cu3O7-α structure. It has been established that the system is heterogeneous at 0.15≤δ≤0.5 and consists of metallic and dielectric regions. The former arises due to oxygen enrichment while the later due to oxygen deficiency. The integral of exchange interaction between Gd3+ localized moments and conduction electrons Jsf=0.016 eV has been determined from the normal state temperature dependence of Gd3+ EPR linewidth for metallic regions. Tc depression by gadolinium-localized moments for GdBa2Cu3O7-α was estimated to be ΔTc{reversed tilde equals}-2K. Anomalies in linewidth temperature dependence upon transition from the normal to the superconducting state have given information about the value and temperature behavior of the superconductor's energy gap. The model, which gives the opportunity to understand some peculiarities of the EPR signal for YBa2Cu3O7-α samples, is proposed in terms of several bottlenecked spinsubsystems: spin-liquid in CuO planes and Cu2+-O- and Cu2+-O2- fragments in CuO chains. © 1989 Plenum Publishing Corporation

Change in the chemical potential of niobium at transition to the superconducting state

A temperature-modulation technique was applied to investigate change in the chemical potential of niobium film at transition to the superconducting state. The first derivative of the chemical potential is continuous at Tc whereas the second derivative shows a jump

Magnetostriction of MnF

Magnetostriction and magnetization of MnF2 samples are measured at several temperatures from T = 4.2 to 70 K in fields up to 14 T directed along and perpendicular to the easy-axis direction [001]. Obtained results confirm the thermodynamic description of magnetostriction proposed earlier

Magnetostriction of terbium molybdate in high magnetic field

Magnetostriction and magnetization M of Tb2(MoO4)3 samples are measured at temperatures T = 4.2 and 20 K in fields H up to 14 T directed along the polar axis [001]. Results of the magnetostriction measurements obey the first law of thermodynamics: -MH = TΔS - WE, where ΔS is the change of the entropy and WE is the work of internal electric field done when ions move due to the magnetostriction

Classical magnetostriction of nickel in high magnetic field

Thermodynamical description of the classical magnetostriction is proposed. Magnetostriction and magnetization of nickel are measured in fields up to 14 T. The change of the chemical potential of electrons is measured in fields up to 10 T. The experimental results are in a reasonable agreement with the theory. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 200675.80.+q Magnetomechanical and magnetoelectric effects, magnetostriction, 05.70.-a Thermodynamics,

Quadrupolar Magnetic Field Outside Antiferromagnetic Cr2\text{}_{2}O3\text{}_{3}

Predicted by Dzyaloshinskii quadrupolar magnetic field outside antiferromagnet was experimentally observed for Cr$\text{}_{2}$O$\text{}_{3}$ single crystal. The magnetic quadrupole sharply disappeared with heating the sample above T$\text{}_{N}$=317 K and appeared again on cooling below T$\text{}_{N}$. The obtained value of the magnetic quadrupole is in reasonable agreement with theoretical estimation

Magnetic properties of nanosized MgFe2O4 powders prepared by auto-combustion

peer reviewedTargets were prepared to be used for magnetron sputtering and laser ablation and their microstructural and magnetic properties were investigated. The base material was nanosized MgFe2O4 powder produced by citrate auto-combustion synthesis. The auto-combusted powders were annealed at temperatures in the range 600 - 1000°C in air to study the effect of temperature on thofe formation MgFe2O4. The saturation magnetization Ms was 24.30 emu/g at room temperature. © Published under licence by IOP Publishing Ltd