Betancourth, D., V. F. Correa, and D. J. García. "Evidence of a Low Energy Anisotropy in GdCoIn_5." Journal of Low Temperature Physics 179, no. 1-2 (2015): 90–93.
Abstract: We investigate the effects of an applied magnetic field on the magnetic properties of the antiferromagnet GdCoIn 5 . The prominent anisotropy observed in the susceptibility below TN is rapidly suppressed by a field of just a few Tesla. Further evidence of this low energy-scale is obtained from magnetoresistance and magnetostriction experiments. The lattice length, particularly, shows a sudden change below 2 T when the magnetic field is applied perpendicular to the crystallographic c^ -axis.
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El-Khatib, S., A. M. Alsmadi, V. Correa, A. V. Andreev, A. Lacerda, F. Nasreen, and H. Nakotte. "Electronic properties of single crystalline UNi[sub 0.39]Rh[sub 0.61]Al." Journal of Applied Physics 103, no. 7 (2008): 07B714–3.
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Encina, S., and P. Pedrazzini. "Low Temperature Thermoelectric Power of Ce(Pd{1-x}Cux)2Si2." Journal of Low Temperature Physics 179, no. 1-2 (2015): 21–27.
Abstract: We present the thermoelectric power S(T) of the Ce(Pd 1−x Cu x ) 2 Si 2 alloy for temperatures \(1.5\,\mathrm{K} K. We observe three characteristic features across the \(0 substitution range: two positive maxima and a negative minimum, that are typical for Ce compounds that display, or lie close to, magnetism. Our analysis of the data shows that the high- T maximum is related to the Kondo effect on excited crystal-field levels, but that the low- T one cannot be simply associated with the Kondo scale, TK . We speculate that disorder induced by alloying can be at the origin of this discrepancy and can also be responsible for the low S(T) measured at low temperatures in the \(0.2 concentration range. We have extended electrical resistivity measurements on Ce(PdCu)Si 2 ( x=0.5 ) down to T∼40 mK in applied fields as high as 16 T.
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Franco, D. G., R. E. Carbonio, and G. Nieva. "Magnetic Properties of the Double Perovskites LaPbMSbO6 (M = Mn, Co, and Ni)." IEEE Transactions on Magnetics 49, no. 8 (2013): 4594–4597.
Abstract: New double perovskites LaPbMSbO6, where M2+ = Mn2+, Co2+, and Ni2+, were synthesized as polycrystals by an aqueous synthetic route at temperatures below 1000 °C. All samples are monoclinic, space group P21/n, as it is observed from Rietveld analysis of X-ray powder diffraction patterns. The distribution of M2+ and Sb5+ among the two octahedral sites have 3% of disorder for M2+ = Ni2+, whereas for M2+ = Mn2+ and Co2+ less disorder is found. The three samples have an antiferromagnetic transition, due to the antiferromagnetic coupling between M2 + through super-superexchange paths M2+-O2--Sb5+-O2--M2+. Transition temperatures are low: 8, 10 and 17 K for Mn2+, Co2+, and Ni2 + respectively, as a consequence of the relatively long distances between the magnetic ions M2+. Besides, for LaPbMnSbO6 a small transition at 45 K was found, with ferrimagnetic characteristics, possibly as a consequence of a small disorder between Mn2+ and Sb5+. This disorder would give additional and shorter interaction paths: superexchange Mn2+-O2--Mn2+.
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Franco, D. G., V. C. Fuertes, M. C. Blanco, M. T. Fernández-Díaz, R. D. Sánchez, and R. E. Carbonio. "Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions." Journal of Solid State Chemistry 194 (2012): 385–391.
Abstract: The synthesis, structural characterization, and magnetic properties of La3Co2SbO9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P21/n. Co2+ and Sb5+ have the maximum order allowed for the La3Co2SbO9 stoichiometry. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a=5.6274(2) Å, b=5.6842(2) Å, c=7.9748(2) Å and β=89.999(3)°. Magnetization measurements indicate the presence of ferromagnetic correlations with TC=55 K attributed to the exchange interactions for non-linear Co2+–O–Sb5+–O–Co2+ paths. The effective magnetic moment obtained experimentally is μexp=4.38 μB (per mol Co2+), between the theoretical one for spin only (3.87 μB) and spin-orbit value (6.63 μB), indicating partially unquenched contribution. The low magnetization value at high magnetic field and low temperature (1 μB/f.u., 5 T and 5 K) and the difference between ZFC and FC magnetization curves (at 5 kOe) indicate that the ferromagnetism do not reach a long range order and that the material has an important magnetic frustration.
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Haberkorn, N., G. Bridoux, E. Osquiguil, G. Nieva, and J. Guimpel. "Hall effect in a GdBa2Cu3O7-?/La0.75 Sr0.25MnO3 perovskite bilayer." Applied Surface Science 254, no. 1 SPEC. ISS. (2007): 222–224.
Abstract: We present results on the Hall coefficient RH in the normal state for a GdBa2Cu3O7-?/La0.75 Sr0.25MnO3 bilayer and a La0.75Sr0.25MnO3 film grown by dc magnetron sputtering on (1 0 0) SrTiO3. We find that the electric transport on the bilayer can be qualitatively described using a simple parallel layers model. The GdBa2Cu3O7-? layer presents a carrier density approximately equal to that reported for 7 – ? = 6.85 oxygen doping. Also we observe an unexpected presence of two Hall resistivity regimes, effects that may be associated with the internal magnetic field induced on the superconducting layer by the ferromagnetic layer.
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Pedrazzini, P., D. Jaccard, G. Lapertot, J. Flouquet, Y. Inada, H. Kohara, and Y. Onuki. "Probing the extended non-Fermi liquid regimes of MnSi and Fe." Physica B – Condensed Matter 378-380 (2006): 165–166.
Abstract: Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe spans over an unexpectedly broad pressure range, between the critical pressure p and around 2p. In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity ρ(T)˜A(p)T at higher pressures. We find that in MnSi the n=32 exponent holds below 4.8GPa≈3p, but it increases above that pressure. At 7.2 GPa we observe the low-temperature Fermi liquid exponent n=2 whereas for T>1.5K, n=53. Our measurements in Fe show that the NFL behavior ρ˜T extends at least up to 30.5 GPa, above the entire superconducting (SC) region. In the studied pressure range, the onset of the SC transition reduces by a factor 10 down to Tconset(30.5GPa)=0.23K, while the A—coefficient diminishes monotonically by around 50%.
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Sereni, J. G., M. Gomez Berisso, A. Braghta, G. Schmerber, and J. P. Kappler. "Unstable Shastry-Sutherland phase in Ce2Pd2Sn." Physical Review B – Condensed Matter and Materials Physics 80, no. 2 (2008): 022428.
Abstract: Thermal (CP) , magnetic ( M and χac ), and transport (Ï) measurements on Ce2Pd2Sn are reported. High-temperature properties are well described by the presence of two excited crystal-field levels at (65±5)K and (230±20)K , with negligible hybridization (Kondo) effects. According to literature, two transitions were observed at TM=4.8K and TC=2.1K , respectively. The upper transition cannot be considered as a standard antiferromagnetic because of frustration effects in a triangular network of Ce atoms and the positive sign of the paramagnetic temperature θPLT=4.4K . The nature of the intermediated phase is described accounting for the formation of ferromagnetic (F) Ce dimers disposed in a quasi-two-dimensional square lattice, resembling a Shastry-Sutherland pattern. According to hysteretic features in Ï(T) and χac(T) , the lower F transition is of first order, with CP(T<TC) revealing a gap of anisotropy Eg≈7K .
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Sirena, M., E. Kaul, M. B. Pedreros, C. A. Rodriguez, J. Guimpel, and L. B. Steren. "Structural, magnetic and electrical properties of ferromagnetic/ferroelectric multilayers." Journal of Applied Physics 109, no. 12 (2011): 123920.
Abstract: The La0.75Sr0.25MnO3 (LSMO)/Ba0.7Sr0.3TiO3 (BSTO) superlattices and bilayers, where LSMO is ferromagnetic and BSTO is ferroelectric, were grown by dc sputtering. X-ray diffraction indicates that the samples present a textured growth with the c axis perpendicular to the substrate. Magnetization measurements show a decrease of the sample’s magnetization for decreasing ferromagnetic thickness. This effect could be related to the presence of biaxial strain and a magnetic dead layer in the samples. Conductive atomic force microscopy indicates that the samples present a total covering of the ferromagnetic layer for a ferroelectric thickness higher than four unit cells. Transport tunneling of the carriers seems to be the preferred conduction mechanism through the ferroelectric layer. These are promising results for the development of multiferroic tunnel junctions.
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