J. L. Sarrao

Los Alamos National Laboratory

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J. D. Thompson

Los Alamos National Laboratory

293

Z. Fisk

University of California, Irvine

197

P. G. Pagliuso

Universidade Estadual de Campinas (UNICAMP)

188

E. D. Bauer

Los Alamos National Laboratory

162

R. Movshovich

Los Alamos National Laboratory

N. O. Moreno

Universidade Federal de Sergipe

M. F. Hundley

Central Washington University

M. F. Hundley

Los Alamos National Laboratory

A. Bianchi

Université de Montréal

Svilen Bobev

University of Delaware

Cooperative Institutions

Los Alamos National Laboratory

283

National High Magnetic Field Laboratory

Florida State University

Argonne National Laboratory

Centre National de la Recherche Scientifique

The University of Tokyo

University of Illinois Urbana-Champaign

Oak Ridge National Laboratory

Universidade Estadual de Campinas (UNICAMP)

University of Florida

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{mu}SR studies of Li-doped La{sub 2}CuO{sub 4}

L. P. Le R. H. Heffner D. E. MacLaughlin Kazutoshi Kojima G. M. Luke

Magnetic properties of the Li-doped cuprates La{sub 2}Cu{sub 1{minus}x}Li{sub x}O{sub 4} (where x = 0.01, 0.05, 0.10, 0.45, and 0.50) have been studied by {mu}SR. For low Li concentrations (x {le} 0.10) the authors find a rapid suppression of T{sub N} as x increases, but little change in the magnitude and temperature dependence of the AFM order parameter. This indicates that Li doping effectively destroys AFM without strongly affecting the onsite Cu moments and the shape of the spinwave excitation spectrum. For high Li concentrations they find magnetic clusters in about 15% of the sample volume; the remaining volume is non-magnetic, suggesting possible single-state formation.

10.2172/244665

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Coexistence of antiferromagnetic order and unconventional superconductivity in heavy-fermionCeRh1−xIrxIn5

Physical Review B (2004)

Guo-qing Zheng N. Yamaguchi Hiroki Kan Y. Kitaoka J. L. Sarrao

We present a systematic ^{115}In NQR study on the heavy fermion compounds CeRh_{1-x}Ir_xIn_5 (x=0.25, 0.35, 0.45, 0.5, 0.55 and 0.75). The results provide strong evidence for the microscopic coexistence of antiferromagnetic (AF) order and superconductivity (SC) in the range of 0.35 \leq x \leq 0.55. Specifically, for x=0.5, T_N is observed at 3 K with a subsequent onset of superconductivity at T_c=0.9 K. T_c reaches a maximum (0.94 K) at x=0.45 where T_N is found to be the highest (4.0 K). Detailed analysis of the measured spectra indicate that the same electrons participate in both SC and AF order. The nuclear spin-lattice relaxation rate 1/T_1 shows a broad peak at T_N and follows a T^3 variation below T_c, the latter property indicating unconventional SC as in CeIrIn_5 (T_c=0.4 K). We further find that, in the coexistence region, the T^3 dependence of 1/T_1 is replaced by a T-linear variation below T\sim 0.4 K, with the value \frac{(T_1)_{T_c}}{(T_1)_{low-T}} increasing with decreasing x, likely due to low-lying magnetic excitations associated with the coexisting magnetism.

10.1103/physrevb.70.014511

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Citations (59)

Pressure–temperature–composition phase diagram of

Physica B Condensed Matter (2006)

E. N. Hering H. A. Borges S. M. Ramos M. B. Fontes E. Baggio‐Saitovitch

Ambient pressure

10.1016/j.physb.2006.01.401

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Citations (4)

Suppressed Andreev reflection at the normal-metal/heavy-fermion superconductor CeCoIn 5 interface

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2005)

Wan Kyu Park L. H. Greene J. L. Sarrao J. D. Thompson

In order to probe the order parameter symmetry of the heavy-fermion superconductor (HFS) CeCoIn₅, we employ point-contact spectroscopy, where dynamic conductance spectra are taken from a nano-scale junction between a normal-metal (N) Au tip and a single crystal of CeCoIn₅. The point-contact junction (PCJ) is formed on a single crystal surface with two crystallographic orientations, (001) and (110). Our conductance spectra, reproducibly obtained over wide ranges of temperature, constitute the cleanest data sets ever reported for HFSs. The point contacts are shown to be in the Sharvin limit, ensuring spectroscopic nature of the measured data. A signature for the emerging heavy-fermion liquid is evidenced by the development of the asymmetry in the background conductance, starting at T* (~ 45 K) and increasing with decreasing temperature down to T_c (2.3 K). Below T_c, an enhancement of the sub-gap conductance arising from Andreev reflection is observed, with the magnitude of ~ 13.3% and ~ 11.8% for the (001) and the (110) PCJ, respectively. These values are an order of magnitude smaller than those observed in conventional superconductors, but consistent with those in other HFSs. Our zero-bias conductance data for the (001) PCJ are best fit with the extended Blonder-Tinkham-Klapwijk model using the d-wave order parameter. The fit to the full conductance curve of the (001) PCJ at 400 mK indicates the strong coupling nature (2Δ/k_BT_c = 4.64). However, our observed suppression of both the Andreev reflection signal and the energy gap indicates the failure of existing models. We provide possible directions for theoretical formulations of the electronic transport across an N/HFS interface in general, and the Au/CeCoIn₅ interface in particular. Several qualitative features observed in the (110) PCJ provide the first clear spectroscopic evidence for the d_x2_-y2 symmetry of the superconducting order parameter in CeCoIn₅.

Andreev reflection

Heavy fermion superconductor

Interface (matter)

Reflection

10.1117/12.622251

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Citations (3)

Structural, magnetic, and transport properties ofLa2Cu1−<…

Physical review. B, Condensed matter (1996)

J. L. Sarrao David P. Young Z. Fisk E. Moshopoulou J. D. Thompson

Li substitutes for Cu in ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$ up to the limiting stoichiometry ${\mathrm{La}}_{2}$${\mathrm{Cu}}_{0.5}$${\mathrm{Li}}_{0.5}$${\mathrm{O}}_{4}$, which has superstructure order. The effects of this in-plane hole doping on the structural and magnetic properties of ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$ are very similar to those due to Sr substitution. The tetragonal-orthorhombic structural phase transition occurs, for a given amount of Sr or Li, at nearly the same temperature, and the in-plane lattice constant of ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Sr}}_{\mathit{y}}$${\mathrm{Cu}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Li}}_{\mathit{x}}$${\mathrm{O}}_{4}$ at room temperature depends only on the combined hole count (x+y) and not on the individual Sr or Li concentration. Long-range magnetic order is destroyed upon substituting 3% Li for Cu, analogous to the effect of Sr substitution on ${\mathit{T}}_{\mathrm{N}\mathrm{\'e}\mathrm{el}}$. However, the holes introduced by Li substitution are bound. The resistivity as a function of temperature is nonmetallic for all Li concentrations. \textcopyright{} 1996 The American Physical Society.

Tetragonal crystal system

Orthorhombic crystal system

10.1103/physrevb.54.12014

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Citations (50)

Evidence for spiral magnetic order in the heavy fermion materialCeRhIn5

Physical review. B, Condensed matter (2000)

N. J. Curro P. C. Hammel P. G. Pagliuso J. L. Sarrao J. D. Thompson

We report ${}^{115}\mathrm{In}$ nuclear quadrupolar resonance measurements of the heavy fermion compound ${\mathrm{CeRhIn}}_{5}$ in the paramagnetic and antiferromagnetic states. The magnetic order is consistent with a model of helical modulation of the Ce moments that is incommensurate with the lattice, and the magnetic dynamics indicate possible two-dimensional behavior.

10.1103/physrevb.62.r6100

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Citations (97)

Magnetic polaron and Fermi surface effects in the spin-flip scattering ofEuB6

Physical Review B (2004)

R. R. Urbano P. G. Pagliuso C. Rettori S. B. Oseroff J. L. Sarrao

The spin-flip scattering (SFS) between conduction and $4{f}^{7}\phantom{\rule{0.3em}{0ex}}{\mathrm{Eu}}^{2+}$ $(^{8}S_{7∕2})$ electrons in the paramagnetic phase of $\mathrm{Eu}{\mathrm{B}}_{6}$ $(T\ensuremath{\geqslant}2{T}_{c}\ensuremath{\simeq}30\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ is studied by means of electron spin resonance (ESR) at three frequencies. The single Dysonian resonance observed in all cases suggests a metallic environment for the ${\mathrm{Eu}}^{2+}$ ions. The ESR at high field, $H\ensuremath{\simeq}12.05\phantom{\rule{0.3em}{0ex}}\mathrm{kG}$ $(\ensuremath{\nu}\ensuremath{\simeq}33.9\phantom{\rule{0.3em}{0ex}}\mathrm{GHz})$, has an anisotropic linewidth with cubic symmetry. The low-field, $1.46\phantom{\rule{0.3em}{0ex}}\mathrm{kG}$ $(4.1\phantom{\rule{0.3em}{0ex}}\mathrm{Ghz})$ and $3.35\phantom{\rule{0.3em}{0ex}}\mathrm{kG}$ $(9.5\phantom{\rule{0.3em}{0ex}}\mathrm{GHz})$, ESR linewidths are unexpectedly broader and have a smaller anisotropy than at the higher field. The unconventional narrowing and anisotropy of the linewidth at higher fields are indicative of a homogeneous resonance and microscopic evidence for a strong reduction in spin-flip scattering between the spins of ${\mathrm{Eu}}^{2+}$ and the states in the electron and hole pockets at the $X$ points of the Brillouin zone by magnetic polarons.

10.1103/physrevb.70.140401

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Citations (37)

Interplay of magnetism, structure and superconductivity in heavy-fermion systems CeMIn5 and PuMGa5

Journal of Alloys and Compounds (2005)

J. D. Thompson M. Nicklas V. A. Sidorov E. D. Bauer R. Movshovich

Magnetism

Isostructural

Cooper pair

10.1016/j.jallcom.2005.04.036

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Structure and Properties of Gd₃Ge₄: The Orthorhombic RE₃Ge₄ Structures Revisited (RE = Y, Tb−Tm)

Inorganic Chemistry (2007)

Paul H. Tobash Gary DiFilippo Svilen Bobev N. Hur J. D. Thompson

The new binary compound Gd3Ge4 has been synthesized and its structure has been determined from single-crystal X-ray diffraction. Gd3Ge4 crystallizes in the orthorhombic space group Cmcm (No. 63) with unit cell parameters a = 4.0953(11) Å, b = 10.735(3) Å, c = 14.335(4) Å, and Z = 4. Its structure can be described as corrugated layers of germanium atoms with gadolinium atoms enclosed between them. The bonding arrangement in Gd3Ge4 can also be derived from that of the known compound GdGe (CrB type) through cleavage of the zigzag chains in GdGe and a subsequent insertion of an extra germanium atom between the resulting triangular fragments. Formally, these characteristics represent isotypism with the Er3Ge4 type (Pearson's oC28). However, re-examination of the crystallography in the whole RE3Ge4 series (RE = Y, Tb−Tm) revealed discrepancies and called into question the accuracy of the originally determined structures. This necessitated a new rationalization of the bonding, which is provided in the context of a comparative discussion concerning both the original and revised structure models, along with an analysis of the trends across the series. The temperature dependence of the magnetic susceptibility of Gd3Ge4 shows that it is paramagnetic at room temperature and undergoes antiferromagnetic ordering below 29 K. Magnetization, resistivity, and calorimetry data for several other members of the RE3Ge4 family are presented as well.

Orthorhombic crystal system

10.1021/ic7009034

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Citations (22)

Ferromagnetism and crystal fields inYbInNi4

Physical review. B, Condensed matter (1998)

J. L. Sarrao R. Modler R. Movshovich A. H. Lacerda Daniela Hristova

We present transport and thermodynamic measurements as a function of temperature (0.1--300 K), pressure (1 bar--16 kbars), and magnetic field (0--600 kOe) on ${\mathrm{YbInNi}}_{4}.$ Ferromagnetism arises near 3 K out of a state with enhanced electronic specific-heat coefficient. Resistivity, specific-heat, and magnetization measurements imply that the ground state of ${\mathrm{YbInNi}}_{4}$ is a crystal-field doublet, whereas earlier neutron-scattering results suggest a ground-state quartet. We also compare ${\mathrm{YbInNi}}_{4}$ to ${\mathrm{YbInCu}}_{4}$ and intermediate alloys.

Bar (unit)

Crystal (programming language)

10.1103/physrevb.57.7785

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Citations (21)