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Cecilia Blanco, M., J. M. De Paoli, S. Ceppi, G. Tirao, V. M. Nassif, J. Guimpel, and R. E. Carbonio. "Synthesis, structural characterization and magnetic properties of the monoclinic ordered double perovskites BaLaMSbO6, with MÂ =Â Mn, Co and Ni." Journal of Alloys and Compounds 606 (2014): 139–148.
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Fernandez, G. E., M. G. Berisso, O. Trovarelli, and J. G. Sereni. "Comparative study of the ferro-antiferromagnetic transition in Ce(Fe,Co)(2) and Ce(Fe,Al)(2)." Journal of Alloys and Compounds 261, no. 1-2 (1997): 26–31.
Abstract: The magnetic, thermal and transport properties of Ce(Fe,Co)(2) and Ce(Fe,Al)(2) around the ferro-antiferromagnetic (F-AF) transition are studied and compared in their thermodynamic aspects. We confirm the presence of a structural contribution to the enthalpy of the transition in the case of Co substitution, which is the main difference between the AF phase transitions in both systems. The role of the Ce hybridization in the Co case and the ''canted'' nature of the AF phase in Ce(Fe,Al)(2) are discussed. (C) 1997 Elsevier Science S.A.
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Luzuriaga, J. "Sphere on a vibrating reed for measurements of turbulence in superfluid helium." Journal of Alloys and Compounds (2000): 265–268.
Abstract: A modification of the vibrating reed, in which a massive sphere is made to oscillate at the end of a cantilevered beam, has been used for measurements in superfluid helium. The apparatus operates in the same way as a conventional vibrating reed with capacitive detection and drive. However, when operating submerged in the liquid, the frequency changes give information on the superfluid fraction, and the dissipation can be used to obtain information on the change of liquid flow, from laminar to turbulent. The spherical geometry allows an exact calculation of all parameters in the laminar regime, so departures due to the turbulence can be better quantified. The method has been found to work well in practice, and some measurements on the turbulent regime in the superfluid are presented.
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Maple, M. B., B. W. Lee, J. J. Neumeier, G. Nieva, L. M. Paulius, and C. L. Seaman. "Hybridization, hole localization and pair breaking in the high Tc superconducting system Y1-xPrxBa2Cu3O7-δ." Journal of Alloys and Compounds 181, no. 1-2 (1992): 135–152.
Abstract: The Y1-xPrxBa2Cu3O7-δ (δ ≈ 0.05) system has a rich temperature—praseodymium concentration (T-x) phase diagram consisting of a metal—insulator transition at xcr≈0.6, high Tc superconductivity in the metallic phase (0x≤xcr), and antiferromagnetic ordering of the Cu2+ and praseodymium ions at Néel temperatures TN(Cu) >TN(Cu)>TN(Pr) in the insulating phase (xcr≤x1). In the metallic phase, Tc decreases monotonically with x and vanishes near xcr, the dependence of Tc on pressure P and the upper critical field on temperature are both anomalous, and the low temperature specific heat can be resolved into a large γΓ contribution, reminiscent of heavy fermion behavior, and a spin Kondo anomaly; in the insulating phase, the values of TN(Pr) are anomalously large. These phenomena are briefly reviewed within the framework of a picture that is based on appreciable hybridization of the praseodymium localized 4f states and the CuO2 valence band states. A phenomenological model that incorporates the annihilation of mobile holes in the CuO2 planes and superconducting electron pair breaking by the praseodymium ions can describe Tc (x,P) for x ≤ 0.2.
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Osquiguil, E., M. Maenhoudt, B. Wuyts, Y. Bruynseraede, D. Lederman, G. Nieva, J. Guimpel, and I. K. Schuller. "Photoexcitation effects in YBa2Cu3Ox." Journal of Alloys and Compounds 195, no. C (1993): 667–670.
Abstract: We show through photoexcitation experiments carried out on YBa2Cu3Ox c-axis oriented films that photoinduced phenomena are not restricted to insulating samples. Superconducting films with critical temperatures varying between 2 K and 40 K show a clear enhancement of the superconducting transition after illumination. The increase in Tc is accompanied by a corresponding decrease in the resistivity ?, and an increase in the Hall coefficient RH, indicative of an increased carrier density. Furthermore, the carrier mobility is also affected by illumination.
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Sanchez, R. D., M. T. Causa, J. G. Sereni, M. Vallet-Regi, M. J. Sayaguez, and J. M. Gonzalez-Calbet. "Specific heat, magnetic susceptibility and electrical resistivity measurements on LaNiO3." Journal of Alloys and Compounds 191, no. 2 (1993): 287–289.
Abstract: Measurements of specific heat, magnetic susceptibility and electrical resistivity on LaNiO3 are reported. No evidence of magnetic ordering or metal-insulator transitions is found. From the measured electronic specific heat parameter γ and the Pauli susceptibility χP, a Stoner enhancement parameter is derived. Comparison with band structure calculations performed by other workers is also made.
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SERENI, J. G. "SYSTEMATICS ON THE CERIUM MAGNETIC-TRANSFORMATIONS INDUCED BY ALLOYING." JOURNAL OF ALLOYS AND COMPOUNDS 207 (1994): 229–236.
Abstract: A systematic study on the competition between on-site and inter-site magnetic interactions is performed on Ce intermetallics through magnetic, thermal, transport, structural and spectroscopic measurements analyses. It is shown that the volume and the electronic concentration variation produced by alloying the Ce-ligand, are not equivalent and only the volume reduction. produces the maximum in the ordering temperature predicted by theory. For the magnetic to intermediate valence transformations, a change of regime is observed at a critical Ce-ligand substitution, which corresponds to a change in the substitution dependence of the experimental parameters. On the contrary, no change of regime is detected for the magnetic to heavy fermion transformation. The different regimes are correlated with the respective hybridization strengths of the ground and excited crystalline field states through the temperature dependence of the electrical resistivity. Such a correlation allows us to draw a generalized phase diagram containing these types of transformation.
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Sutter, J. G., A. S. Chávez, S. Soria, M. Granada, L. Neñer, S. Bengió, P. Granell, F. Golmar, N. Haberkorn, A. G. Leyva et al. "Tuning the magneto-electrical properties of multiferroic multilayers through interface strain and disorder." Journal of Alloys and Compounds (2020): 157820.
Abstract: Artificially engineered superlattices were designed and fabricated to induce different growth mechanisms and structural characteristics. DC sputtering was used to grow ferromagnetic (La0.8Ba0.2MnO3)/ferroelectric (Ba0.25Sr0.75TiO3 or BaTiO3) superlattices. We systematically modified the thickness of the ferromagnetic layer to analyze dimensional and structural disorder effects on the superlattices with different structural characteristics. The crystalline structure was characterized by X-ray diffraction and transmission electron microscopy. The magnetic and electronic properties were investigated by SQUID magnetometry and resistance measurements. The results show that both strain and structural disorder can significantly affect the physical properties of the systems. Ba0.25Sr0.75TiO3 based superlattices with a low thickness of the ferromagnetic layers (4 nm.) present compressive strain that decreases the ferromagnetic transition temperature from 250 K corresponding to the unstressed samples to 230 K. In these samples, the localization energy of the charge carrier through the electron-phonon interaction decreases at low temperatures (∼100 meV). Ba0.25Sr0.75TiO3 based superlattices with thicknesses of the ferromagnetic layers higher than 12 nm present tensile strain that reduces the charge carrier localization energy at low temperatures (∼1 meV), increasing the ferromagnetic transition temperature (Tc∼265K). Structural defects in BaTiO3 based superlattices have a stronger influence on the magnetic properties than on the transport properties. Nevertheless, disorder blocks the ferromagnetic transition for highly disordered samples (thickness of the ferromagnetic layer < 3 nm). These results help to further understand the role of strain and interface effects in the magnetic and transport properties of manganite based multiferroic systems.
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Sutter, J. G., A. Sarmiento Chávez, S. Soria, M. Granada, L. Neñer, S. Bengió, P. Granell, F. Golmar, N. Haberkorn, A. G. Leyva et al. "Tuning the magneto-electrical properties of multiferroic multilayers through interface strain and disorder." Journal of Alloys and Compounds 859 (2021): 157820.
Abstract: Artificially engineered superlattices were designed and fabricated to induce different growth mechanisms and structural characteristics. DC sputtering was used to grow ferromagnetic (La0.8Ba0.2MnO3)/ferroelectric (Ba0.25Sr0.75TiO3 or BaTiO3) superlattices. We systematically modified the thickness of the ferromagnetic layer to analyze dimensional and structural disorder effects on the superlattices with different structural characteristics. The crystalline structure was characterized by X-ray diffraction and transmission electron microscopy. The magnetic and electronic properties were investigated by SQUID magnetometry and resistance measurements. The results show that both strain and structural disorder can significantly affect the physical properties of the systems. Ba0.25Sr0.75TiO3 based superlattices with a low thickness of the ferromagnetic layers (4 nm) present compressive strain that decreases the ferromagnetic transition temperature from 250 K corresponding to the unstressed samples to 230 K. In these samples, the localization energy of the charge carrier through the electron-phonon interaction decreases at low temperatures (∼100 meV). Ba0.25Sr0.75TiO3 based superlattices with thicknesses of the ferromagnetic layers higher than 12 nm present tensile strain that reduces the charge carrier localization energy at low temperatures (∼1 meV), increasing the ferromagnetic transition temperature (Tc∼265 K). Structural defects in BaTiO3 based superlattices have a stronger influence on the magnetic properties than on the transport properties. Nevertheless, disorder blocks the ferromagnetic transition for highly disordered samples (thickness of the ferromagnetic layer < 3 nm). These results help to further understand the role of strain and interface effects in the magnetic and transport properties of manganite based multiferroic systems.
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Trovarelli, O., M. Gomez-Berisso, P. Pedrazzini, D. Bosse, C. Geibel, J. G. Sereni, and F. Steglich. "Metallurgic, structural and magnetic properties of Ce(Pd1-rRhr)(2)Si-2." JOURNAL OF ALLOYS AND COMPOUNDS 275 (1998): 569–573.
Abstract: We report on investigations of the metallurgic, crystallographic and magnetic properties of the Ce(Pd1-rRhr)(2)Si-2 system. While the as-cast samples show a miscibility gap for 0.3<r<0.7, complete miscibility with a monotonous evolution of the lattice parameters is found in samples annealed at 1200 degrees C. Although both pure compounds order antiferromagnetically at 10 K (r=0) and 36 K (r=1) respectively, our magnetic susceptibility (chi) results indicate a magnetically non-ordered state at intermediate concentrations. The ordering temperature decreases smoothly and continuously on the Pd-rich side, vanishing between r=0.2 and r=0.3. On the Rh-rich side, this decrease is faster and at r=0.8 the long-range magnetic order is replaced by enhanced magnetic fluctuations as evidenced by a broad maximum in chi(T) around 25 K. The orientation-dependent chi of the strongly textured samples indicates an evolution towards an easy-axis system with increasing Rh content. The results are discussed and compared to the related systems Ce(Pd1-xTx)(2)Si-2 (T=Ru and Cu). (C) 1998 Elsevier Science S.A.
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