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Superconducting YBa2Cu3O6+x (YBCO) films are grown by pulsed laser deposition (PLD) in the orientation where its c-axis is lying in the plane of the film using (110) oriented SrTiO3 (STO) substrates with PrBCO template layer. By optimization of deposition temperature and rate the easily formed (103) orientation was avoided to get smooth and completely (110) oriented YBCO films. To improve the superconducting properties, we have also optimized the BaZrO3 (BZO)-doping in the (110) YBCO films. This gives the possibility to apply the current along the YBCO CuO2 planes where the critical current is much higher in thin film multilayers or to investigate the anisotropy and the effect of BZO pinning structure in different film orientations.

We report the effect of 4 wt% BZO-doping in GdBCO thin films on (100) STO substrates with novel nanograined target materials deposited by pulsed laser deposition (PLD) method. X-ray diffraction, atomic force microscopy and magnetization measurements, which were made in particularly wide temperature and magnetic field range, were used to determine the structural and superconducting properties. The results were compared with ones of YBCO. The deposition temperature, T s, is not very critical for GdBCO and it is found to be much lower in undoped and BZO-doped GdBCO than in YBCO. The BZO-doping of GdBCO enhanced the field dependence of critical current density, j c, at low temperatures. Furthermore, BZO-doping enhances the accommodation field, B* , below 60 K being clearly higher at 10 K in doped GdBCO than in YBCO. The pinning mechanism in GdBCO was concluded to be similar to that of YBCO. Our results clearly show that undoped and BZO-doped nanophase GdBCO is a very promising target material for applications as well as for coated conductors.

Thin YBa2Cu3O6+x (YBCO) films are prepared by pulsed laser deposition (PLD) from pure micro- (mu) and nanocrystalline (n) targets and a n-target optimally doped with 3.9 wt% BaZrO3 (BZO). Effects of target grain size and doping on superconducting (SC) properties of the films are investigated using a SQUID magnetometer up to 5 T and transport measurements in pulsed magnetic fiefds up to 30 T. In comparison with mu-films, clearly increased values of jc are observed in n-films. Optimal doping with BZO still increases this difference in high magnetic field range and lengthens the low-field plateau of jc(B) and increases the accommodation field B* which are typically around 110 mT, 160 mT and 500 mT at 5 K in mu-, n- and BZO-doped films, respectiveiy. Transport measurements at T > 65 K show significant improvement of irreversibiiity line (IRL) and jc(B) in films prepared from n-target and BZO-doped target. These improvements of the superconducting properties in high magnetic fiefds make pure and BZO-doped n-films attractive for high field applications.

Magnetic susceptibility, M-H plot, magnetoresistance and thermoelectric power of the RuSr2Eu1.5Ce0.5Cu2O10 superconductor are measured. Values of the magnetic transition temperature Tmag, superconductivity transition temperature Tc, upper critical field Hc2, chemical potential mu, and energy width for electric conduction W(sigma) are obtained from these measurements. It has been found that Tmag = 140 K, Tc = 25 K (33 K) from susceptibility (magnetoresistance) measurements, Hc2 (0) > 32 T, mu = 8 meV, and W(sigma) = 58.5 meV. These values are compared with other ruthenate superconductors, and resulting physical information is discussed., 18 pages of TEXT + FIGS. To appear in - J. PHYS. COND. MATT. (2006)

YBCO thin films were prepared by pulsed laser deposition from a pure nanocrystalline YBCO target and similar targets doped with BaZrO/sub 3/ or Y/sub 2/BaCuO/sub 5/ (Y211 phase) in order to investigate the effect of these impurities on magnetic flux pinning. The doped targets were pressed from nanopowders prepared by a sol-gel method from starting solutions whose nominal molar ratios corresponded to compositions YBCO+2.2 and 6.5 wt% BaZrO/sub 3/ and YBCO+3.0 wt% Y211 phase. The biggest changes in the superconducting properties relative to the films prepared from the pure target were observed in the films ablated from the BaZrO/sub 3/-doped targets. Although the doping reduces the critical temperature, the critical current density calculated from the hysteresis loops is significantly increased in external magnetic fields above 0.15 T. Addition of Y211 to the target is found not to be as effective for improving the flux pinning of the films in high magnetic fields as addition of the BaZrO/sub 3/. J/sub c/'s in zero field and 77 K were 1.2 MA/cm/sup 2/ in the pure YBCO film, 1.1 MA/cm/sup 2/ in the 2.2 wt% BaZrO/sub 3/ doped film and 3.2 MA/cm/sup 2/ in the 3.0 wt% Y211 doped film.

Magnetophonon resonance in quantum wells in a tilted magnetic field B is investigated. Measurements of the Hall coefficient and correspondingly of the carrier concentration as a functions of magnetic field and temperature are simultaneously performed. It is shown that the experimental data can be interpreted in terms of a great sensitivity to the effects of varying the two dimensional carrier concentration ns in a certain concentration interval. In other words, the observed angular dependence of the MPR amplitudes is a manifestation of dependence of ns on the magnitude of the magnetic field B. We believe that such a dependence can be relevant in general for the interpretation of magnetotransport in nondegenerate 2D electron gas.

Thermally induced motion and clustering of single particles obtained by pulsed laser deposition (PLD) from an YBa/sub 2/Cu/sub 3/O/sub 6+x/ target having nanosize grains is investigated. As shown by atomic force microscopy the as-deposited particles on SrTiO/sub 3/ substrates have average height of 1-3 unit cells and width of 40 nm. When the substrate is post-annealed after deposition in oxygen at a temperature T/sub a/ 400/spl deg/C the particles start to grow in height and simultaneously their surface density on the substrate decreases. Only when most of the particles have reached the height of 10 nm their width begins to grow, increasing continuously as T/sub a/ is risen up to 900/spl deg/C. The way of coalescence of the particles upon increasing T/sub a/ is compared with island growth models of thin films prepared by PLD. It is suggested that these particles could be used for manufacture of nanostructures fusing them together by thermal annealing.

The process of teleportation of a completely unknown single-photon relativistic state is considered. Analysis of the relativistic case reveals that the teleportation as it is understood in the non-relativistic quantum mechanics is impossible if no {\it a priori} information on the state to be teleported is available. It is only possible to speak of the amplitude of the propagation of the field (taking into account the measurement procedure) since the existence of a common vacuum state together with the microcausality principle (the field operators commutation relations) make the concept of the propagation amplitude for the individual subsystems physically meaningless. When partial {\it a priori} information is available (for example, only the polarization state of the photon is unknown while its spatial state is specified beforehand), the teleportation does become possible in the relativistic case. In that case the {\it a priori} information can be used to ``label'' the identical particles to make them effectively distinguishable., Comment: 9 pages

We report the first observation of the polarization dependence of the d.c. photocurrent induced by illumination in Cu. The dependence of a d.c. photocurrent on the direction of the plane of light polarization is measured. In agreement with the theoretical considerations, the current parallel to the plane of light incidence is a symmetric function of the angle between this plane and the plane of light polarization. The angular-dependent part of the current perpendicular to the plane of light incidence is an antisymmetric function of the angle.

AdetailedstudyofthemagneticandtransportpropertiesofSi1−xMnx (x ≈ 0.35)filmsispresented.Weobserve the anomalous Hall effect in these films up to room temperature. The results of the magnetic measurements and the anomalous Hall effect data are consistent and demonstrate the existence of long-range ferromagnetic order in the systems under investigation. A correlation of the anomalous Hall effect and the magnetic properties of the samples with their conductivity and substrate type is shown. A theoretical model based on the idea of a two-phase magnetic material, in which molecular clusters with localized magnetic moments are embedded in the matrix of a weak itinerant ferromagnet, is discussed and used to explain experimental results. The long-range ferromagnetic order at high temperatures is mainly due to the Stoner enhancement of the exchange coupling between clusters through thermal spin fluctuations (“paramagnons”) in the matrix. Theoretical predictions do not contradict experimental data when model parameters of a plausible order of magnitude are used.

A novel method for the synthesis of composite nanomaterials is suggested. Glassy carbon–metal (Au, Ag) composite materials are obtained in which the carbon matrix contains mesopores and metals are present in the form of nanoparticles distributed over the matrix. The sizes of nanoparticles are 10 and 23 nm for Au and Ag, respectively, while the specific surface area of the pores of materials ranges from 25 to 300 m2/g. A surprisingly high magnetic susceptibility of Au and Ag composites is revealed. © 2015, (publisher). All rights reserved.

Magnetic properties of the semimagnetic semiconductor (Zn 1-x Mn x ) 3 As 2 (for short, ZMA) with 0.001≤x≤0.13 have been investigated at temperatures between 4 and 300 K. It is shown that the magnetic susceptibilities of the samples cooled in zero external field (ZFC) and in a field (FC) are different for compositions with x≥0.02. At Mn concentrations 0.08≤x≤0.13 freezing of the moments is observed around T f ∼200 K

Magnetoelectrical measurements were performed on diodes and bulk heterojunction solar cell blends (BHSCs) to clarify the role of formation of Coulombically bound electron-hole (e-h) pairs on the magnetoresistance (MR) response in organic thin-film devices. BHSCs are suitable model systems because they effectively quench excitons but the probability of forming e-h pairs in them can be tuned over orders of magnitude by the choice of material and solvent in the blend. We have systematically varied the e-h recombination coefficients, which are directly proportional to the probability for the charge carriers to meet in space, and found that a reduced probability of electrons and holes meeting in space lead to the disappearance of the MR. Our results clearly show that MR is a direct consequence of the e-h pair formation. We also found that the MR line shape follows a power-law dependence of ${B}^{0.5}$ at higher fields.

Magnetoresistance (MR) of oriented single crystals of the anisotropic semiconductor p-CdSb doped with 2 at% of Ni is investigated between T =1.5 and 300 K in transversal pulsed magnetic fields up to B =30 T. In fields B ∼4–15 T at T below 4.2 K, the resistivity obeys the law ln ρ ∼ η [ Bϕ ( B )] 1/2 with ϕ ( B )= a (0)/ a ( B ), where a is the carrier localization radius and parameter η depends on a (0), on the acceptor concentration N A and on the direction of the magnetic field with respect to the crystallographic axes, but does not depend on T . Such behavior gives evidence for MR realized by hopping charge transfer over the nearest-neighbor sites in strong magnetic field. The analysis of the experimental data yields the values of η , agreeing with calculated ones within an error of 10%, taking into account the effects of the anisotropy of the acceptor states and of the explicit dependence of a ( B ) due to the increase in the activation energy of shallow acceptors in magnetic field and the sensitivity of the metal–insulator transition to B .

We report results of investigations of structural and transport properties of GaAs/Ga(1-x)In(x)As/GaAs quantum wells (QWs) having a 0.5-1.8 ML thick Mn layer, separated from the QW by a 3 nm thick spacer. The structure has hole mobility of about 2000 cm2/(V*s) being by several orders of magnitude higher than in known ferromagnetic two-dimensional structures. The analysis of the electro-physical properties of these systems is based on detailed study of their structure by means of high-resolution X-ray diffractometry and glancing-incidence reflection, which allow us to restore the depth profiles of structural characteristics of the QWs and thin Mn containing layers. These investigations show absence of Mn atoms inside the QWs. The quality of the structures was also characterized by photoluminescence spectra from the QWs. Transport properties reveal features inherent to ferromagnetic systems: a specific maximum in the temperature dependence of the resistance and the anomalous Hall effect (AHE) observed in samples with both "metallic" and activated types of conductivity up to ~100 K. AHE is most pronounced in the temperature range where the resistance maximum is observed, and decreases with decreasing temperature. The results are discussed in terms of interaction of 2D-holes and magnetic Mn ions in presence of large-scale potential fluctuations related to random distribution of Mn atoms. The AHE values are compared with calculations taking into account its "intrinsic" mechanism in ferromagnetic systems., 15 pages, 9 figures

Mo doped ruthenocuprates ${\mathrm{Ru}}_{1\ensuremath{-}x}{\mathrm{Mo}}_{x}{\mathrm{Sr}}_{2}{\mathrm{Eu}}_{1.5}{\mathrm{Ce}}_{0.5}{\mathrm{Cu}}_{2}{\mathrm{O}}_{10\ensuremath{-}\ensuremath{\delta}}$ are synthesized for $x=0.0$, 0.2, 0.4, 0.6, 0.8, and 1.0, and their magnetic and superconducting properties are studied. It has been found that the magnetic transition temperature $T_{\mathit{ZFC}}{}^{\text{peak}}$, which corresponds to the appearance of a weak ferromagnetic effect, decreases from its value of $75\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for $x=0.0$ to 22, 25, and $18\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, respectively for the $x=0.2$, 0.4, and 0.6 samples. Another finding is that the magnetic susceptibility reduces at $T_{\mathit{ZFC}}{}^{\text{peak}}$ by a factor of about 6, 85, and 413 for $x=0.2$, 0.4, and 0.6, respectively. The samples of $x=0.8$ and 1.0 are found to have no magnetic or superconducting effects. The values of the superconducting transition temperature are obtained from the resistivity versus the temperature data. An important result is that ${T}_{c}$ increases by 4.5 and $7.0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for $x=0.2$ and 0.4, respectively, and then decreases by $17\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for $x=0.6$. The observed variation of ${T}_{c}$ with $x$ has been explained in terms of a theory which combines the effects of weakening magnetic behavior and reducing carrier concentration in a phenomenological manner. The resulting theory is found to provide a good agreement with the observed value of ${T}_{c}$.

This is the first report of the observation of the onset of excess volume and also of the strain along the a-axis near the magnetic ordering temperature in Ru-1222 superconductor, and indicates a coupling between the lattice and the magnetism in this system. Magnetization, magneto transport and thermoelectric power measurements being carried out on the same sample are also reported., Comment: 15 Pages Text Plus Figs. Physica C (2006) accepted

Electronic spectra of porous Si have been investigated in the region

A theory of double magnetophonon resonance (MPR) in quantum wells in magnetic field is developed. The magnetic field is assumed to be tilted at an angle θ to the perpendicular to the plane of quantum well. The resonance is due to the resonant interaction of two-dimensional conduction electrons with the longitudinal optic phonons. The electrons are assumed to be nondegenerate. The 0 dependence of MPR maxima is investigated. The existence of a double resonance, i.e., two resonant peaks for each value of N (the number of resonance) and sharpness of the θ dependence is explained by the screening in conjunction with the combined role of the phonon and electon damping and variation of electron concentration in the well with magnetic field.

The process of teleportation of a completely unknown one-particle state of a free relativistic quantum field is considered. In contrast to the non-relativistic quantum mechanics, the teleportation of an unknown state of the quantum field cannot be in principle described in terms of a measurement in a tensor product of two Hilbert spaces to which the unknown state and the state of the EPR-pair belong. The reason is of the existence of a cyclic (vacuum) state common to both the unknown state and the EPR-pair. Due to the common vacuum vector and the microcausality principle (commutation relations for the field operators), the teleportation amplitude contains inevitably contributions which are irrelevant to the teleportation process. Hence in the relativistic theory the teleportation in the sense it is understood in the non-relativistic quantum mechanics proves to be impossible because of the impossibility of the realization of the appropriate measurement as a tensor product of the measurements related to the individual subsystems so that one can only speak of the amplitude of the propagation of the field as a whole., Comment: 11 pages

Low-field (B = 10 G – 1 kG) magnetic properties are investigated in ceramic samples of La1–xSrxMn1−yFeyO3 (LSMFO) with x = 0.3 and y = 0.15, 0.20 and 0.25. A substantial decrease of the ferromagnetic (FM) Curie temperature, TC, with increasing y is observed, which is connected to breaking of the FM double-exchange interactions by doping with Fe. Strong magnetic irreversibility at B = 10 G gives evidence for a frustrated magnetic state of LSMFO. The asymptotic Curie-Weiss behaviour of the magnetic susceptibility, χ (T), observed well above TC, yields the values of the effective Bohr magneton per magnetic ion, exceeding considerably those of single ions. Critical behaviour of χ (T) ~ (T/TC – 1) −γ is influenced at y = 0.15 and 0.20 by a percolative (γ ≈ 1.8) and non-percolative or Heisenberg (γ ≈ 1.4) spin systems. At y = 0.25 the percolative contribution to χ (T) is not observed. The low-field magnetic properties above can be explained by the phase separation effect or generation of nanosize FM particles in the paramagnetic host matrix of LSMFO.

The resistivity, , is investigated in ceramic La1-xSrxMn1-yFeyO3 samples with x = 0.3 and y = 0.03  0.25 at temperatures T ~ 5  310 K in magnetic fields B up to 8 T. The metallic conductivity at y = 0.03 and the variable-range hopping (VRH) conductivity between y = 0.15  0.25 are observed. The Mott VRH conductivity takes place in all investigated samples with y ≥ 0.15 in different temperature intervals. In addition, at y = 0.25 the interval of the Shklovskii- Efros VRH conductivity, characteristic of the Coulomb gap in the density of the localized states (DOS), is observed. Analysis of the VRH conductivity yields the values of the microscopic parameters, including the DOS features and the localization radii of charge carriers.

A series of studies has been carried out on thin films which were prepared by pulsed laser deposition from micro-grained targets of Y1-xPrxBa2Cu3O7-? (Y1-xPrxBCO) to determine the doping effect of Pr (at Y site) in concentrations between x = 0 ?0.20. Earlier results on bulk materials show that the Pr substitution can significantly enhance the value of Jc(B) at cost of Tc. Our X-ray diffraction results confirmed the good quality of the films without any impurity phases. Magnetometric studies show the systematic decrease of Jc(B) when the Pr concentration is increased.

We report the effect of magnetic impurities in the spacer layer of polymeric spin valves (PSV) with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/π-conjugated polymer regio-random poly(3-hexyl thiophene)/cobalt (Co), showing giant magnetoresistance (GMR) response. Different deposition rates of Co at the top electrode resulted in two types of devices: one with lower device resistance and linear current–voltage (I–V) characteristics and the other with very low inclusion of Co and exhibiting higher device resistance and nonlinear I–V characteristics. We observed an asymmetric dc bias dependence of magnetoresistance (MR) in devices with more Co inclusion, while for the other type of device, bias dependence was more symmetric. At higher bias, %MR of both types of device showed no significant difference (5–10%), but at low dc bias it ranged between 50 and 160% MR. This can be attributed to the higher tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other. Magnetic tunnel junction-like features are observed in the devices with greater Co inclusions. Anomalous MR peaks were also observed in these devices and their origin was explained in terms of presence of additional scattering centers around the included metal ions and increased spin relaxation due to high magnetic anisotropy in the system. Both types of PSVs showed a monotonic decrease in MR with temperature at high bias currents.