Papers by Hortencio Borges
Measurements of the electrical resistivity of U/sub 1/minus/x/ Th/sub x/ Be/sub 13/ compounds as ... more Measurements of the electrical resistivity of U/sub 1/minus/x/ Th/sub x/ Be/sub 13/ compounds as a function of pressure provide a possible explanation for the unusual behavior of these materials. 10 refs., 2 figs.
Physica B+C, 1987
Resistivity of (Th, U)Bet3 under pressure may show the restoration of the onset of electron coher... more Resistivity of (Th, U)Bet3 under pressure may show the restoration of the onset of electron coherence. Unseparated rare earth elements can be used for preparation of high-T c superconductors.
Physica B: Condensed Matter, 2009
In this work, we report on the physical properties of good-quality polycrystalline superconductin... more In this work, we report on the physical properties of good-quality polycrystalline superconducting samples of La 2Àx Sr x Cu 1Ày Zn y O 4Àd (y ¼ 0, 0.02) prepared by a wet-chemical method, focusing on the temperature dependence of the critical current. Using the wet-chemical method, we were able to produce samples with improved homogeneity compared to the solid-state method. A complete set of samples with several carrier concentrations, ranging from the underdoped (strontium concentration xE0.05) to the highly overdoped (xE0.25) region, were prepared and investigated. The X-ray diffraction analysis, zero-field cooling magnetization and electrical resistivity measurements were reported on earlier. The structural parameters of the prepared samples seem to be slightly modified by the preparation method and their critical temperatures were lower than reported in the literature. The temperature dependence of the critical current was explained by a theoretical model which took the granular structure of the samples into account.
Physica B+C, 1987
We report electrical resistance and magnetoresistance measurements on EuBa2(Cu 1 yZnv)30 x under ... more We report electrical resistance and magnetoresistance measurements on EuBa2(Cu 1 yZnv)30 x under pressures to 17kbar. With Zn substitution, T c is depressed rapidly (-19K/at.%Zn) and there are qualitative changes in the temperature and field response of the resistance. Pressure drives the Zn-substituted samples toward undoped EuBa2Cu30 ~ behavior. Analysis of the temperature dependent resistance for y =0.05 and P = 0, together with Hall effect and thermopower data, suggests that the suppression of superconductivity may arise from weak three-dimensional localization promoted by Coulomb interactions.
We report electrical resistance and magnetoresistance measurements on EuBa/sub 2/(Cu/sub 1-y/Zn/s... more We report electrical resistance and magnetoresistance measurements on EuBa/sub 2/(Cu/sub 1-y/Zn/sub y/)/sub 3/O/sub x/ under pressure to 17 kbar. With Zn substitution, T/sub c/ is depressed rapidly (approx.19 K/at.% Zn) and there are qualitative changes in the temperature and field response of the resistance. Pressure drives the Zn-substituted samples toward undoped EuBa/sub 2/Cu/sub 3/O/sub x/ behavior. Analysis of the temperature dependent resistance for y = 0.05 and P = O, together with Hall effect and thermopower data, suggests that the suppression of superconductivity may arise from weak three-dimensional localization promoted by Coulomb interactions.
ABSTRACT We report the discovery of pressure-induced superconductivity in single crystalline Ce_2... more ABSTRACT We report the discovery of pressure-induced superconductivity in single crystalline Ce_2RhIn_8. At atmospheric pressure, Ce_2RhIn8 exhibits a large electronic specific heat (gamma=400 mJ/molCe K^2) above its Néel temperature T_N=2.8 K. A second magnetic transition develops at T_LN=1.6 K. Hydrostatic pressure very rapidly suppresses T_LN, while 25-30 kbar is required to drive TN to zero. A zero-resistance diamagnetic state below T_c=0.6 K appears at P=16.3 kbar. Tc reaches a maximum of 2 K near 25 kbar. The phase diagram of Ce_2RhIn8 is compared to that of family members CeIn3 and CeRhIn_5.
Physical Review B, 1987
We have determined the eAect of pressure P on the resistance and superconducting transition tempe... more We have determined the eAect of pressure P on the resistance and superconducting transition temperature T, of RBa2Cu30 (R =Gd, Er, and Yb) and compare our results to those obtained on high-quality YBa2Cu30. The transition temperature, which is 90 K or greater at ambient pressure for all four compounds, is enhanced by pressure in each at rates between 0.09 and 0. 19 K/kbar. Interestingly, the presence of a localized moment in the rare-earth compounds appears to have no influence on the pressure response. From the positive dT, /dP we infer a positive change in the thermal expansion upon entering the superconducting state.
Physical Review B, 2004
Pressure studies of CeRh1−xIrxIn5 indicate two superconducting phases as a function of x, one wit... more Pressure studies of CeRh1−xIrxIn5 indicate two superconducting phases as a function of x, one with Tc ≥ 2 K for x < 0.9 and the other with Tc < 1.2 K for x > 0.9. The higher Tc phase, phase-1, emerges in proximity to an antiferromagnetic quantum-critical point; whereas, Cooper pairing in the lower Tc phase-2 is inferred to arise from fluctuations of a yet to be found magnetic state. The T-x-P phase diagram of CeRh1−xIrxIn5, though qualitatively similar, is distinctly different from that of CeCu2(Si1−xGex)2.
Physical Review B, 2007
Page 1. Antiferromagnetic quantum criticality in CeCoGe2.1Si0.9 under pressure M. Alzamora,1,* MB... more Page 1. Antiferromagnetic quantum criticality in CeCoGe2.1Si0.9 under pressure M. Alzamora,1,* MB Fontes,2 J. Larrea J.,2 HA Borges,1 EM Baggio-Saitovitch,2 and SN Medeiros3 1Departamento de Física, Pontifícia Universidade ...
Journal of Magnetism and Magnetic Materials, 1988
Journal of Applied Physics, 1988
Heavy fermion behavior in CePISi and CeRySf L. Rebeisky, K. Reilly, and S. Horn Department of Phy... more Heavy fermion behavior in CePISi and CeRySf L. Rebeisky, K. Reilly, and S. Horn Department of Physks, New York University, New York, New York I0Q03 H. Borges, JD Thompson, J. O, Willis, and R. Aikfn Los Alamos National Laboratory, Los Alamos, New Mexico 87545 R. ...
Novel Superconducting Materials, 2016
BiS2-based compounds constitute a new family of layered superconductors. In this article, several... more BiS2-based compounds constitute a new family of layered superconductors. In this article, several experimental findings on the superconductivity and related properties of the BiS2 family are reviewed. In particular, the focus is on the conditions required for the emergence of superconductivity and higher superconducting transition temperature in the BiS2 family: it is shown that optimizing the electron doping and crystal structure are important. Further, a few notable characteristics such as the coexistence of superconductivity and magnetism as well as the relation between the superconductivity and chargedensity- wave instability are introduced in brief.
Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions, 1987
Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions, 1987
Journal of Applied Physics, 2015
Philosophical Magazine Part B, 1996
Physica B: Condensed Matter, 2006
We have determined the effect of pressure P on the resistance and superconducting transition temp... more We have determined the effect of pressure P on the resistance and superconducting transition temperature T/sub c/ of RBaâCuâO/sub x/ (R = Gd, Er, and Yb) and compare our results to those obtained on high quality YBaâCuâO/sub x/. The transition temperature, which is 90 K or greater at ambient pressure for all four compounds, is enhanced by pressure in each
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Papers by Hortencio Borges