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Ale Crivillero, M. V., N. Haberkorn, G. Nieva, and J. Guimpel. "Electrical transport properties of FeSe/Fe3O4 bilayers." Materials Today: Proceedings 14 (2019): 18–21.
Abstract: In this work, we study the electronic properties of FeSe/Fe3O4 bilayers deposited onto SrTiO3 (100) and MgO (100) substrates by DC magnetron sputtering. The comparative study of Fe3O4 films grown on SrTiO3 and MgO reveals significant differences in the intensity of the Verwey transition (Tv∼130K). This allows us to probe the impact of the distortions associated to the Verwey transition on the transport properties of the FeSe over-layer in the FeSe/Fe3O4 bilayers. A correlated increase in the resistance and weakened superconducting properties are observed..
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Aragón Sánchez, J., R. Cortés Maldonado, M. I. Dolz, N. R. CejasBolecek, C. J. van der Beek, M. Konczykowski, and Y. Fasano. "Direct visualization of local interaction forces in Bi2Sr2CaCu2O8+δ vortex matter." Materials Today: Proceedings 14 (2019): 34–37.
Abstract: We study the local vortex-vortex interaction force fi of the structure frozen during a field-cooling process in an electron-irradiated Bi2Sr2CaCu2O8+δ sample. We compute this magnitude from snapshots of the vortex structure obtained via magnetic decoration experiments at various fields H in the same sample. Since the observed structures correspond to the equilibrium ones frozen at T∼Tirr(H)[1], at this temperature the local modulus of fi roughly equals the local pinning force at the decorated surface of the sample. We estimate the most probable local pinning force from the mode value of the fi(r)distribution, fpm. We found that fpm grows algebraically with H and in electron-irradiated samples is 50-20% smaller than for samples with columnar defects.
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Morán M., Condó A. M., Soldera F., Sirena M. and Haberkorn N. "Thickness dependence of the martensitic transformation in textured Cu-Al-Ni thin films grown by sputtering on Si (001)." Materials Today: Proceedings 14 (2019): 96–99.
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Rumi, G., L. J. Albornoz, P. Pedrazzini, M. I. Dolz, H. Pastoriza, C. J. van der Beek, M. Konczykowski, and Y. Fasano. "Entropy jump at the first-order vortex phase transition in Bi2Sr2CaCu2O8+δ with columnar defects." Materials Today: Proceedings 14 (2019): 30–33.
Abstract: We study the entropy jump associated with the first-order vortex melting transition (FOT) in Bi2Sr2CaCu2O8+δ crystals by means of Hall probe magnetometry. The samples present a diluted distribution of columnar defects (CD) introduced by irradiation with Xe ions. The FOT is detected in ac transmittivity measurements as a paramagnetic peak, the height of which is proportional to the enthalpy difference entailed by the transition. By applying the Clausius-Clapeyron relation, we quantify the evolution of the entropy jump Δs as a function of the FOT temperature, TFOT, in both pristine crystals and crystals with CD. On increasing the density of CD, Δs decreases monotonically with respect to values found in pristine samples. The Δs versus TFOT dependence in the case of pristine samples follows reasonably well the theoretical prediction of dominant electromagnetic coupling for a model neglecting the effect of disorder. The data for samples with a diluted distribution of CD are not properly described by such a theoretical model.
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Sereni, J. G. "Analysis of Entropy trajectories in very Heavy Fermions for Adiabatic Demagnetization Refrigeration at the T<1K range." Materials Today: Proceedings 14 (2019): 67–71.
Abstract: With the aim to improve classical paramagnetic salts performances for adiabatic magnetization refrigeration processes, relevant thermodynamic parameters of recently discovered very heavy fermion Yb-based intermetallic compounds are investigated within the sub-Kelvin range of temperature. Focusing on fixed thermal points, required for e.g. photonic devices operating within the 100 mK range in orbital satellites, the nature of respective magnetic ground states are discussed together with the effect of an 'entropy bottleneck' imposed by the Nernst postulate the entropy S(T) trajectories. To gain insight into the main criteria for a proper choice of suitable materials for alternative applications, thermomagnetic S(T,B) trajectories and respective derivatives: δS/δT and δS/δB, are analyzed as key parameters for this magnetocaloric process and compared with those from the classical salt Cerium-Magnesium-Nitride (CMN).
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Sereni, J. G., J. Roberts, F. Gastaldo, M. Gómez Berisso, and M. Giovannini. "Shastry-Sutherland phase formation in magnetically frustrated Ce2Pd2In1-xSnx alloys." Materials Today: Proceedings 14 (2019): 80–83.
Abstract: Taking profit that the ternary indides Ce2+εPd2-εIn form two branches of solid solutions allowing to access to ferromagnetic (FM, ε > 0) or anti-ferromagnetic (AFM, ε < 0) ground states depending on the relative Ce/Pd concentration 'ε' , we have tested the possibility of a Shastry-Sutherland phase formation by electron doping the trivalent In lattice with tetravalent Sn. Starting from the AFM, ε < 0 side provides the lowest electron concentration conditions increasing the sensitivity to electron doping. For such a purpose low temperature thermal and magnetic properties were investigated on Ce2+εPd2-εIn1-xSnx alloys within the 0 ≤ x ≤ 0.6 range of concentration.
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