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Multilayered cuprates possess not only the highest superconducting temperature transition but also offer a unique platform to study disorder-free CuO$_2$ planes and the interplay between competing orders with superconductivity. Here, we study the underdoped trilayer cuprate HgBa$_2$Ca$_2$Cu$_3$O$_{8+ δ}$ and we report the first quantum oscillation and Hall effect measurements in magnetic field up to 88 T. A careful analysis of the complex spectra of quantum oscillations strongly supports the coexistence of an antiferromagnetic order in the inner plane and a charge order in the outer planes. The presence of an ordered antiferromagnetic metallic state that extends deep in the superconducting phase is a key ingredient that supports magnetically mediated pairing interaction in cuprates., 6+5 pages, 4+6 figures

The incidence of topology on the band structure and physical properties of layered compounds has been extensively studied in semimetals. How those evolve in presence of electronic correlations has been less investigated so far. In the sodium cobaltates NaxCoO2 considered here, unexpected magnetic properties associated with correlations on the Co sites have been disclosed about 15 years ago. The distinct Na orders of the stable phases of these cobaltates have been shown to induce specific Co charge disproportionation with large size unit cells in the CoO2 planes, linked with the diverse magnetic behaviors. This provides an original playground in the studies of interplays between topology and correlations in these layered materials. We present here transport measurements on a series of single crystals and demonstrate that we do synthetize pure phases with quite reproducible transport properties. We show that above room T those display a similar behavior whatever the Na content. On the contrary we provide evidence for a great diversity in Hall effect low temperature dependences which underlines the specificities of the Fermi Surface reconstructions induced by the Na order. We study in some detail the difference between two metallic phases, one (x = 0.77) antiferromagnetic below TN = 22 K and the second (x = 2/3) paramagnetic down to T = 0. Both show a sign change in the Hall effect with decreasing T. We demonstrate that this can be attributed to quite distinct physical effects. For the x = 0.77 phase the negative Hall effect occurs in similar conditions to the anomalous Hall effect found in various magnetic metals. In the x = 2/3 phase have to be assigned to specificities of its Fermi surface. In both cases the anomalies detected in the Hall effect are certainly associated with the topology of their Co electronic bands., Comment: 9 figures

© 2016 Published under licence by IOP Publishing Ltd. Here we present the investigation of the orthorhombic o-LuFeO 3 thin film grown on SrTiO 3 (001) substrate. Temperature dependencies of magnetization measured in magnetic fields 1000 Oe and 2000 Oe were described in the assumption that ferromagnetic correlated regions are presented in samples together with the paramagnetic phase. Additional argument in favor of the ferromagnetic regions existence in o-LuFeO 3 is the magnetic hysteresis curve measured at T=5 and 100K. The temperature dependences of dielectric response were measured and analyzed.

© 2017 Elsevier B.V. (La 0.7 Sr 0.3 MnO 3 ) x (CaCu 3 Ti 4 O 12 ) 1−x (0.01 ≤ x ≤ 0.3) nanostructured composites with La 0.7 Sr 0.3 MnO 3 (LSMO) microinclusions in CaCu 3 Ti 4 O 12 (CCTO) matrix were synthesized using a solid state method. The structural and microstructural details were studied by X-ray diffraction (XRD), X-ray fluorescence (XFA), scaning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The magnetic properties were studied by electron spin resonance (ESR) and magnetometry methods. In the concentration range 0.01 < x < 0.1 physical properties of composites differ from the properties of the individual components CCTO or LSMO. The Curie temperature of the ferromagnetic phase for all concentrations is T C = 315 K, that is less at 50 K than in pure LSMO. The Weiss constant of the paramagnetic phase has the strong concentration dependance. The observed mutual influence on the magnetic properties of both components can be tentatively attributed to the interface exchange interactions between them, hinting a possible magnetic proximity effect.

© Published under licence by IOP Publishing Ltd.We present the results of magnetic and Mössbauer effect studies of zinc oxide thin film obtained by RF magnetron sputtering and implanted with 40 keV iron ions to a fluence of 1.5•1017 ion/cm2. As-implanted and post-annealed sample shows ferromagnetic properties at room temperature and consists of paramagnetic and ferromagnetic phases according to Mössbauer spectroscopy.

© 2017 O. I. Medvedeva et al. A series of cobalt (Co) and its oxides based nanoparticles were synthesized by using hyperbranched polyester polyol Boltorn H20 as a platform and sodium borohydride as a reducing agent. UV, FT-IR, XRD, NTA, and TEM methods were employed to obtain physicochemical characteristics of the products. The average diameter of Co nanoparticles was approximately 8.2±3.4 nm. Their magnetic properties, including hysteresis loop, field-cooled, and zero field-cooled curves were investigated. The nanoparticles exhibit superparamagnetism at room temperature, accompanied by magnetic hysteresis below the blocking temperature.

© 2016 Elsevier B.V.Here we report the magnetic susceptibility measurements of magnetron sputtered orthorhombic manganite RMnO3 (R=Yb, Gd) thin films deposited on dielectric LaAlO3 and ferroelectric SrTiO3, LiNbO3 substrates. We observed that all of investigated o-RMnO3 films show a splitting in the temperature dependence of ZFC and FC magnetization curves. We found that the substrate can impact on the splitting temperature ZFC-FC curves and absolute value of the magnetization of thin films.

© 2017 Elsevier B.V. (SrFe 12 O 19 ) x (CaCu 3 Ti 4 O 12 ) 1-x (x = 0.01, 0.03, 0.07, 0.1) composites were synthesized using a solid state method, while the pre-synthesized strontium hexaferrite SrFe 12 O 19 (SFO) was added to the stoichiometric amount of CaO, CuO and TiO oxides to form the CaCu 3 Ti 4 O 12 (CCTO) structure around SFO microinclusions. The structural and microstructural properties of obtained composites were studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. The magnetic properties were studied by electron spin resonance and magnetometry methods. Based on all experimental data we can conclude, that SFO x CCTO 1-x nanostructured composites were formed only for concentrations x = 0.03 and x = 0.07, where SFO nanoinclusions are inside CCTO matrix, that leads to the strong mutual influence of the magnetic properties of both component.

© Kazan Federal University (KFU).[Fe(3-MeO-Qsal)2]Y (Y = PF6, BF4, NCS, NO3, BPh4) compounds were synthesized using the diffusion method and studied by the electron spin resonance and the magnetic susceptibility methods in the temperature range (5-300) K. Coexistence of spatially separated high-spin and low-spin fractions in these compounds was observed. Low-spin fraction of all compounds reveals the antiferromagnetic correlations at low temperatures. High-spin fraction of complexes with Y = PF6 demonstrate the weak ferromagnetic properties due to exchange interaction between complexes in whole temperature range. Influence of outer-sphere anion on the spin state, the electronic properties of low-spin Fe(III) complexes is demonstrated.

© 2016, Pleiades Publishing, Inc.New composite materials (SrFe12O19)x(CaCu3Ti4O12)1–x (x = 0, 0.05, 1) have been synthesized. Their magnetic properties are studied in the temperature range 5–300 K using the magnetic resonance and magnetometry methods. It is found that strontium hexaferrite microinclusions in the (SrFe12O19)0.05(CaCu3Ti4O12)0.95 composite “magnetize” CaCu3Ti4O12 at temperatures from 300 to 200 K, forming a ferrimagnetic particle near the SrFe12O19 “core.” The magnetic resonance line below 200 K splits into two lines corresponding to SrFe12O19 and CaCu3Ti4O12. The core effect decoration is manifested in the increase in the Curie–Weiss temperature from 25 K in CaCu3Ti4O12 without the doping ceramics to 80 K in the composite with 5% of SrFe12O19.

© 2016, Pleiades Publishing, Ltd.[FeLX2]Y [L = N,N'-ethylenebis(salicylimine) (salen), N,N'-ethylenebis(acetylacetonylimine) (acen), or N,N'-ethylenebis(3-methyloxysalicylimine) (vanen); X = imidazole or N-methylimidazole; Y = BF4, ClO4, or BPh4] compounds have been prepared and studied by means of EPR and magnetic susceptibility measurements at 5–300 K. It has been shown that the different electron-donating properties of acen and salen planar ligands result in different spin states of Fe(III) ions. Intermolecular π-interactions of the outer-sphere BPh4 ion affect the complexes spin state as well.

© 2015 American Physical Society. SrEr2O4 is a geometrically frustrated magnet which demonstrates rather unusual properties at low temperatures including a coexistence of long- and short-range magnetic order, characterized by two different propagation vectors. In the present work, the effects of crystal fields (CFs) in this compound containing four magnetically inequivalent erbium sublattices are investigated experimentally and theoretically. We combine the measurements of the CF levels of the Er3+ ions made on a powder sample of SrEr2O4 using neutron spectroscopy with site-selective optical and electron paramagnetic resonance measurements performed on single-crystal samples of the lightly Er-doped nonmagnetic analog, SrY2O4. Two sets of CF parameters corresponding to the Er3+ ions at the crystallographically inequivalent lattice sites are derived which fit all the available experimental data well, including the magnetization and dc susceptibility data for both lightly doped and concentrated samples.

Single crystals of sodium cobaltates NaxCoO2 with x ≈ 0.8 were grown by the floating zone technique. Using electrochemical Na de-intercalation method we reduced the sodium content in the as-grown crystals down to pure phase with 22 K Néel temperature and x ≈ 0.77. The 59Co NMR study in the paramagnetic state of the TN = 22 K phase permitted us to evidence that at least 6 Co sites are differentiated. They could be separated by their magnetic behavior into three types: a single site with cobalt close to non-magnetic Co3+, two sites with the most magnetic cobalts in the system, and the remaining three sites displaying an intermediate behavior. This unusual magnetic differentiation calls for more detailed NMR experiments on our well characterized samples. © 2014 Pleiades Publishing, Inc.

Single crystals of sodium cobaltates Na$_{x}$CoO$_{2}$ with $x \approx 0.8$ were grown by the floating zone technique. Using electrochemical Na de-intercalation method we reduced the sodium content in the as-grown crystals down to pure phase with 22 K N��el temperature and $x \approx 0.77$. The $^{59}$Co NMR study in the paramagnetic state of the $T_{N}=22$ K phase permitted us to evidence that at least 6 Co sites are differentiated. They could be separated by their magnetic behaviour into three types: a single site with cobalt close to non-magnetic Co$^{3+}$, two sites with the most magnetic cobalts in the system, and the remaining three sites displaying an intermediate behaviour. This unusual magnetic differentiation calls for more detailed NMR experiments on our well characterized samples., 5 pages, 4 figures, submitted to JETP Lett

Multilayered cuprates possess not only the highest superconducting temperature transition but also offer a unique platform to study disorder-free CuO2 planes and the interplay between competing orders with superconductivity. Here, we study the underdoped trilayer cuprate HgBa2Ca2Cu3O8+delta and we report quantum oscillation and Hall effect measurements in magnetic field up to 88 T. A careful analysis of the complex spectra of quantum oscillations strongly supports the coexistence of an antiferromagnetic order in the inner plane and a charge order in the outer planes. The presence of an ordered antiferromagnetic metallic state that extends deep in the superconducting phase is a key ingredient that supports magnetically mediated pairing interaction in cuprates.