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Baumbach RE, Lu X, Ronning F, Thompson JD, Bauer ED. Pressure tuned ferromagnetism in CeRu(2)M(2)X (M = Al, Ga; X = B, C). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:325601-7. [PMID: 22809834 DOI: 10.1088/0953-8984/24/32/325601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The temperature (T)-pressure (P) phase diagrams are reported for the tetragonal layered compounds CeRu(2)Al(2)B, CeRu(2)Ga(2)B, and CeRu(2)Ga(2)C, studied by magnetization, specific heat and electrical resistivity. These systems exhibit localized 4f magnetic ordering with ferromagnetic ground states at T(C) = 12.8 K, 16.3 K, and 17.2 K, respectively. Chemical and applied pressure both increase T(C) in a similar manner. The evolution of properties with chemical and applied pressure suggests that these phase diagrams may be connected in a Doniach-like picture where CeRu(2)Al(2)B is furthest from the possible quantum phase transition and CeRu(2)Ga(2)C is the nearest.
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Park WK, Tobash PH, Ronning F, Bauer ED, Sarrao JL, Thompson JD, Greene LH. Observation of the hybridization gap and Fano resonance in the Kondo lattice URu2Si2. PHYSICAL REVIEW LETTERS 2012; 108:246403. [PMID: 23004299 DOI: 10.1103/physrevlett.108.246403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Indexed: 06/01/2023]
Abstract
The nature of the second-order phase transition that occurs in URu2Si2 at 17.5 K remains puzzling despite intensive research. A key question emerging in the field is whether a hybridization gap between the renormalized bands can be identified as the "hidden" order parameter. We report on the measurement of a hybridization gap in URu2Si2 employing a spectroscopic technique based on quasiparticle scattering. The differential conductance exhibits an asymmetric double-peak structure, a clear signature for a Fano resonance in a Kondo lattice. The hybridization gap opens well above 17.5 K, indicating that it is not the hidden order parameter. Our results put stringent constraints on the origin of the hidden order transition in URu2Si2 and demonstrate that quasiparticle scattering spectroscopy can probe the band renormalizations in a Kondo lattice via detection of a novel type of Fano resonance.
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Yasuoka H, Koutroulakis G, Chudo H, Richmond S, Veirs DK, Smith AI, Bauer ED, Thompson JD, Jarvinen GD, Clark DL. Observation of 239Pu nuclear magnetic resonance. Science 2012; 336:901-4. [PMID: 22605773 DOI: 10.1126/science.1220801] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In principle, the spin-½ plutonium-239 ((239)Pu) nucleus should be active in nuclear magnetic resonance spectroscopy. However, its signal has eluded detection for the past 50 years. Here, we report observation of a (239)Pu resonance from a solid sample of plutonium dioxide (PuO(2)) subjected to a wide scan of external magnetic field values (3 to 8 tesla) at a temperature of 4 kelvin. By mapping the external field dependence of the measured resonance frequency, we determined the nuclear gyromagnetic ratio (239)γ(n)(PuO(2))/2π to be 2.856 ± 0.001 megahertz per tesla (MHz/T). Assuming a free-ion value for the Pu(4+) hyperfine coupling constant, we estimated a bare (239)γ(n)/2π value of ~2.29 MHz/T, corresponding to a nuclear magnetic moment of μ(n) ≈ 0.15μ(N) (where μ(N) is the nuclear magneton).
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Baumbach RE, Shang T, Torrez M, Ronning F, Thompson JD, Bauer ED. Local moment ferromagnetism in CeRu2Ga2B. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:185702. [PMID: 22508935 DOI: 10.1088/0953-8984/24/18/185702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Magnetization, specific heat, and electrical resistivity measurements for polycrystalline specimens of CeRu(2)Ga(2)B reveal local moment ferromagnetic order at a Curie temperature T(C) = 16.3 K. Specific heat measurements show that the phase transition is second order and the low temperature behavior indicates that the Ce f-electron states do not hybridize strongly with the conduction electron states. Electrical resistivity measurements demonstrate large spin disorder scattering of conduction electrons for T ≥ T(C). Results for a single crystal are also reported, where T(C) = 15.4 K. While results for the polycrystal and single crystal specimens are qualitatively similar, the differences between them suggest that crystalline disorder plays a role in how the magnetism develops.
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Singh S, Fitzsimmons MR, Lookman T, Thompson JD, Jeen H, Biswas A, Roldan MA, Varela M. Magnetic nonuniformity and thermal hysteresis of magnetism in a manganite thin film. PHYSICAL REVIEW LETTERS 2012; 108:077207. [PMID: 22401251 DOI: 10.1103/physrevlett.108.077207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/14/2011] [Indexed: 05/31/2023]
Abstract
We measured the chemical and magnetic depth profiles of a single crystalline (La(1-x)Pr(x))(1-y)Ca(y)MnO(3-δ) (x=0.52±0.05, y=0.23±0.04, δ=0.14±0.10) film grown on a NdGaO(3) substrate using x-ray reflectometry, electron microscopy, electron energy-loss spectroscopy, and polarized neutron reflectometry. Our data indicate that the film exhibits coexistence of different magnetic phases as a function of depth. The magnetic depth profile is correlated with a variation of chemical composition with depth. The thermal hysteresis of ferromagnetic order in the film suggests a first-order ferromagnetic transition at low temperatures.
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Park T, Lee H, Martin I, Lu X, Sidorov VA, Gofryk K, Ronning F, Bauer ED, Thompson JD. Textured superconducting phase in the heavy fermion CeRhIn5. PHYSICAL REVIEW LETTERS 2012; 108:077003. [PMID: 22401243 DOI: 10.1103/physrevlett.108.077003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Indexed: 05/31/2023]
Abstract
When antiferromagnetism and unconventional superconductivity coexist in CeRhIn(5) there is a significant temperature difference between resistively and thermodynamically determined transitions into the superconducting state. In this state, anisotropic transport near the superconducting transition reveals the emergence of textured superconducting planes that appear without a change in translational symmetry of the lattice. CeRhIn(5) is not unique in exhibiting these behaviors, indicating that textured superconductivity may be a general consequence of coexisting orders in correlated electron materials.
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Bauer ED, Altarawneh MM, Tobash PH, Gofryk K, Ayala-Valenzuela OE, Mitchell JN, McDonald RD, Mielke CH, Ronning F, Griveau JC, Colineau E, Eloirdi R, Caciuffo R, Scott BL, Janka O, Kauzlarich SM, Thompson JD. Localized 5f electrons in superconducting PuCoIn₅: consequences for superconductivity in PuCoGa₅. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:052206. [PMID: 22194040 DOI: 10.1088/0953-8984/24/5/052206] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The physical properties of the first In analog of the PuMGa(5) (M = Co, Rh) family of superconductors, PuCoIn(5), are reported. With its unit cell volume being 28% larger than that of PuCoGa(5), the characteristic spin-fluctuation energy scale of PuCoIn(5) is three to four times smaller than that of PuCoGa(5), which suggests that the Pu 5f electrons are in a more localized state relative to PuCoGa(5). This raises the possibility that the high superconducting transition temperature T(c) = 18.5 K of PuCoGa(5) stems from the proximity to a valence instability, while the superconductivity at T(c) = 2.5 K of PuCoIn(5) is mediated by antiferromagnetic spin fluctuations associated with a quantum critical point.
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Lu X, Lee H, Park T, Ronning F, Bauer ED, Thompson JD. Heat-capacity measurements of energy-gap nodes of the heavy-fermion superconductor CeIrIn5 deep inside the pressure-dependent dome structure of its superconducting phase diagram. PHYSICAL REVIEW LETTERS 2012; 108:027001. [PMID: 22324705 DOI: 10.1103/physrevlett.108.027001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Indexed: 05/31/2023]
Abstract
We use heat-capacity measurements as a function of field rotation to identify the nodal gap structure of CeIrIn(5) at pressures to 2.05 GPa, deep inside its superconducting dome. A fourfold oscillation in the heat capacity at 0.3 K is observed for all pressures, but with its sign reversed between 1.50 and 0.90 GPa. On the basis of recent theoretical models for the field-angle-dependent specific heat, all data, including the sign reversal, imply a d(x(2)-y(2)) order parameter with nodes along [110], which constrains theoretical models of the pairing mechanism in CeIrIn(5).
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Tobash PH, Ronning F, Thompson JD, Scott BL, Moll PJW, Batlogg B, Bauer ED. Single crystal study of the heavy-fermion antiferromagnet CePt₂In₇. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:015601. [PMID: 22133582 DOI: 10.1088/0953-8984/24/1/015601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report the synthesis, structure, and physical properties of single crystals of CePt(2)In(7). Single crystal x-ray diffraction analysis confirms the tetragonal I4/mmm structure of CePt(2)In(7) with unit cell parameters a = 4.5886(6) Å, c = 21.530(6) Å and V = 453.32(14) Å(3). The magnetic susceptibility, heat capacity, Hall effect and electrical resistivity measurements are all consistent with CePt(2)In(7) undergoing an antiferromagnetic order transition at T(N) = 5.5 K, which is field independent up to 9 T. Above T(N), the Sommerfeld coefficient of specific heat is γ ≈ 300 mJ mol(-1) K(-2), which is characteristic of an enhanced effective mass of itinerant charge carriers. The electrical resistivity is typical of heavy-fermion behavior and gives a residual resistivity ρ(0) ∼ 0.2 µΩ cm, indicating good crystal quality. CePt(2)In(7) also shows moderate anisotropy of the physical properties that is comparable to structurally related CeMIn(5) (M = Co, Rh, Ir) heavy-fermion superconductors.
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Sakai H, Brown SE, Baek SH, Ronning F, Bauer ED, Thompson JD. Magnetic-field-induced enhancements of nuclear spin-lattice relaxation rates in the heavy-fermion superconductor CeCoIn5 using 59Co nuclear magnetic resonance. PHYSICAL REVIEW LETTERS 2011; 107:137001. [PMID: 22026890 DOI: 10.1103/physrevlett.107.137001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Indexed: 05/31/2023]
Abstract
(59)Co nuclear spin-lattice relaxation has been measured for the heavy-fermion superconductor CeCoIn(5) in a range of applied fields directed parallel to the c axis. An enhanced normal-state relaxation rate, observed at low temperatures and fields just above H(c2)(0), is taken as a direct measure of the dynamical susceptibility and provides microscopic evidence for an antiferromagnetic instability. The results are well described using the self-consistent renormalized theory for two-dimensional antiferromagnetic spin fluctuations, and parameters obtained in the analysis are applied to previously reported specific heat and thermal expansion data with good agreement.
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Thompson JD, McClarty PA, Gingras MJP. Local susceptibility of the Yb(2)Ti(2)O(7) rare earth pyrochlore computed from a Hamiltonian with anisotropic exchange. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:164219. [PMID: 21471615 DOI: 10.1088/0953-8984/23/16/164219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The rare earth pyrochlore magnet Yb(2)Ti(2)O(7) is among a handful of materials that apparently exhibit no long range order down to the lowest explored temperatures and well below the Curie-Weiss temperature. Paramagnetic neutron scattering on a single crystal sample has revealed the presence of anisotropic correlations and recent work has led to the proposal of a detailed microscopic Hamiltonian for this material involving significantly anisotropic exchange. In this paper, we compute the local sublattice susceptibility of Yb(2)Ti(2)O(7) from the proposed model and compare with the measurements of Cao et al (2009 Phys. Rev. Lett. 103 056402), finding quite good agreement. In contrast, a model with only isotropic exchange and long range magnetostatic dipolar interactions gives rise to a local susceptibility that is inconsistent with the data.
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Altarawneh MM, Harrison N, Sebastian SE, Balicas L, Tobash PH, Thompson JD, Ronning F, Bauer ED. Sequential spin polarization of the Fermi surface pockets in URu2Si2 and its implications for the hidden order. PHYSICAL REVIEW LETTERS 2011; 106:146403. [PMID: 21561207 DOI: 10.1103/physrevlett.106.146403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Indexed: 05/30/2023]
Abstract
Using Shubnikov-de Haas oscillations measured in URu2Si2 over a broad range in a magnetic field of 11-45 T, we find a cascade of field-induced Fermi surface changes within the hidden order phase I and further signatures of oscillations within field-induced phases III and V [previously discovered by Kim et al., [Phys. Rev. Lett. 91, 256401 (2003)]. A comparison of kinetic and Zeeman energies indicates a pocket-by-pocket polarization of the Fermi surface leading up to the destruction of the hidden order phase I at ≈35 T. The anisotropy of the Zeeman energy driving the transitions in URu2Si2 points to an itinerant hidden order parameter involving quasiparticles whose spin degrees of freedom depart significantly from those of free electrons.
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Park T, Sidorov VA, Lee H, Ronning F, Bauer ED, Sarrao JL, Thompson JD. Unconventional quantum criticality in the pressure-induced heavy-fermion superconductor CeRhIn₅. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:094218. [PMID: 21339571 DOI: 10.1088/0953-8984/23/9/094218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The lack of superconductivity in several candidate materials that exhibit a non-spin density wave quantum critical point has raised the question of whether the associated spectra of quantum fluctuations are beneficial to forming superconducting electron pairs. Here we discuss the possibility that the prototypical heavy-fermion antiferromagnet CeRhIn5 may be the first example of unconventional superconductors where superconductivity arises from Kondo-breakdown quantum criticality.
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Bauer ED, Tobash PH, Mitchell JN, Kennison JA, Ronning F, Scott BL, Thompson JD. Magnetic order in Pu₂M₃Si₅ (M = Co, Ni). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:094223. [PMID: 21339576 DOI: 10.1088/0953-8984/23/9/094223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of two new plutonium compounds Pu2M3Si5 (M = Co, Ni) are reported. Pu2Ni3Si5 crystallizes in the orthorhombic U2Co3Si5 structure type, which can be considered a variant of the BaAl4 tetragonal structure, while Pu2Co3Si5 adopts the closely related monoclinic Lu2Co3Si5 type. Magnetic order is observed in both compounds, with Pu2Ni3Si5 ordering ferromagnetically at T(C) = 65 K then undergoing a transition into an antiferromagnetic state below T(N) = 35 K. Two successive magnetic transitions are also observed at T(mag1) = 38 K and T(mag2) = 5 K in Pu2Co3Si5. Specific heat measurements reveal that these two materials have a moderately enhanced Sommerfeld coefficient γ ∼ 100 mJ/mol Pu K(2) in the magnetic state with comparable RKKY and Kondo energy scales.
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Tobash PH, Jiang Y, Ronning F, Booth CH, Thompson JD, Scott BL, Bauer ED. Synthesis, structure and physical properties of YbNi3Al9.23. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:086002. [PMID: 21411905 DOI: 10.1088/0953-8984/23/8/086002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The physical properties of YbNi(3)Al(9.23(1)), including the crystal structure, magnetization, specific heat, valence, and electrical resistivity, are reported. Single crystal x-ray diffraction reveals that the compound crystallizes with the rhombohedral space group R32 and has unit cell parameters a = 7.2443(3) Å and c = 27.251(3) Å with some crystallographic disorder at Al sites. The compound orders antiferromagnetically at T(N) = 3 K despite the presence of strong ferromagnetic correlations, accompanied by a spin-flop-like transition to a moment-aligned state above 0.1 T. X-ray absorption spectroscopy and magnetic susceptibility measurements indicate a localized Yb(3+) electronic configuration, while the Sommerfeld coefficient for the magnetically ordered state was determined as approximately 135 mJ mol(-1) K(-2), suggesting moderately heavy fermion behavior. Therefore, these data indicate a balance between competing Ruderman-Kittel-Kasuya-Yosida (RKKY) and Kondo interactions in YbNi(3)Al(9.23(1)) with a somewhat dominant RKKY interaction that leads to a relatively high ordering temperature.
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Zaum S, Grube K, Schäfer R, Bauer ED, Thompson JD, v Löhneysen H. Towards the identification of a quantum critical line in the (p, B) phase diagram of CeCoIn5 with thermal-expansion measurements. PHYSICAL REVIEW LETTERS 2011; 106:087003. [PMID: 21405592 DOI: 10.1103/physrevlett.106.087003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Indexed: 05/30/2023]
Abstract
The low-temperature thermal expansion of CeCoIn(5) single crystals measured parallel and perpendicular to magnetic fields B oriented along the c axis yields the volume thermal-expansion coefficient β. Considerable deviations of β(T) from Fermi-liquid behavior occur already within the superconducting region of the (B, T) phase diagram and become maximal at the upper critical field B(c2)(0). However, β(T) and the Grüneisen parameter Γ are incompatible with a quantum critical point at B(c2)(0), but allow for a quantum criticality shielded by superconductivity and extending to negative pressures for B<B(c2)(0). We construct a tentative (p, B, T) phase diagram of CeCoIn(5) suggesting a quantum critical line in the (p, B) plane.
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Gofryk K, Sefat AS, McGuire MA, Sales BC, Mandrus D, Imai T, Thompson JD, Bauer ED, Ronning F. Effect of annealing on the specific heat of optimally doped Ba(Fe0.92Co0.08)2As2. ACTA ACUST UNITED AC 2011. [DOI: 10.1088/1742-6596/273/1/012094] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Baek SH, Sakai H, Bauer ED, Mitchell JN, Kennison JA, Ronning F, Thompson JD. Anisotropic spin fluctuations and superconductivity in "115" heavy fermion compounds: ⁵⁹Co NMR study in PuCoGa₅. PHYSICAL REVIEW LETTERS 2010; 105:217002. [PMID: 21231343 DOI: 10.1103/physrevlett.105.217002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 10/03/2010] [Indexed: 05/30/2023]
Abstract
We report results of ⁵⁹Co nuclear magnetic resonance measurements on a single crystal of superconducting PuCoGa₅ in its normal state. The nuclear spin-lattice relaxation rates and the Knight shifts as a function of temperature reveal an anisotropy of spin fluctuations with finite wave vector q. By comparison with the isostructural members, we conclude that antiferromagnetic XY-type anisotropy of spin fluctuations plays an important role in mediating superconductivity in these heavy fermion materials.
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Sidorov VA, Thompson JD, Fisk Z. Magnetic transitions in a heavy-fermion antiferromagnet U2Zn17 at high pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:406002. [PMID: 21386582 DOI: 10.1088/0953-8984/22/40/406002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Pressure-dependent electrical resistivity and ac-calorimetry measurements on single crystals of the heavy-fermion antiferromagnet U(2)Zn(17) at pressures to 5.5 GPa reveal that the low temperature magnetic order changes above ∼3 GPa. The Neél temperature (T(N) = 9.7 K at ambient pressure) decreases slowly for pressures below 3 GPa, but above this pressure a new magnetic state develops at T(M)≈8.7 K. This magnetic phase becomes more stable with pressure increase (dT(M)/dP = 1 K GPa(-1), T(M) = 10.5 K at 5.3 GPa). The heavy-electron state in U(2)Zn(17) is robust against pressure--the electronic specific heat coefficient γ≈0.4 J mol(-1) K(-2) is nearly pressure independent for both magnetic phases. Magnetic ac-susceptibility measurements show that the pressure-induced state is not ferromagnetic.
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Ramos SM, Fontes MB, Hering EN, Continentino MA, Baggio-Saitovich E, Neto FD, Bittar EM, Pagliuso PG, Bauer ED, Sarrao JL, Thompson JD. Superconducting quantum critical point in CeCoIn(5-x)Sn(x). PHYSICAL REVIEW LETTERS 2010; 105:126401. [PMID: 20867661 DOI: 10.1103/physrevlett.105.126401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Indexed: 05/29/2023]
Abstract
We report a combined pressure-doping study in the nearly two-dimensional heavy fermion superconductor CeCoIn5 as its superconducting phase is driven to the normal state by Sn doping and/or applied pressure. Temperature-pressure-dependent electrical resistivity measurements were performed at the vicinity of a superconducting quantum critical point where Tc→0. A universal plot of the concentration- and pressure-dependent phase diagram suggests that for the concentrations studied a single mechanism is responsible for reducing Tc and bringing the system to the superconducting quantum critical point. A two-band model with hybridization controlled by pressure and doping provides a consistent description of the phase diagram and the suppression of the d-wave superconductivity in this material.
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Fisk Z, Hess DW, Pethick CJ, Pines D, Smith JL, Thompson JD, Willis JO. Heavy-electron metals: new highly correlated States of matter. Science 2010; 239:33-42. [PMID: 17820627 DOI: 10.1126/science.239.4835.33] [Citation(s) in RCA: 316] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Heavy-electron metals exhibit highly correlated electronic behavior at liquid helium temperatures, with conduction-electron masses some hundred times the free-electron mass. Whether "normal," antiferromagnetic, or superconducting, their electronic behavior differs drastically from their ordinary metallic counterparts. The physical origin of the large mass and unusual superconducting and magnetic properties is the strong coupling between the conduction electrons and the local f-electron moment fluctuations characteristic of these materials.
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Talbayev D, Burch KS, Chia EEM, Trugman SA, Zhu JX, Bauer ED, Kennison JA, Mitchell JN, Thompson JD, Sarrao JL, Taylor AJ. Hybridization and superconducting gaps in the heavy-fermion superconductor PuCoGa5 probed via the dynamics of photoinduced quasiparticles. PHYSICAL REVIEW LETTERS 2010; 104:227002. [PMID: 20867199 DOI: 10.1103/physrevlett.104.227002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Indexed: 05/29/2023]
Abstract
We have examined the relaxation of photoinduced quasiparticles in the heavy-fermion superconductor PuCoGa5. The deduced electron-phonon coupling constant is incompatible with the measured superconducting transition temperature Tc=18.5 K, which speaks against phonon-mediated superconductivity. Upon lowering the temperature, we observe an order-of-magnitude increase of the quasiparticle relaxation time in agreement with the phonon bottleneck scenario--evidence for a hybridization gap in the electronic density of states. The modification of photoinduced reflectance in the superconducting state is consistent with the heavy character of the quasiparticles that participate in Cooper pairing.
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Kenzelmann M, Gerber S, Egetenmeyer N, Gavilano JL, Strässle T, Bianchi AD, Ressouche E, Movshovich R, Bauer ED, Sarrao JL, Thompson JD. Evidence for a magnetically driven superconducting Q phase of CeCoIn5. PHYSICAL REVIEW LETTERS 2010; 104:127001. [PMID: 20366558 DOI: 10.1103/physrevlett.104.127001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Indexed: 05/29/2023]
Abstract
We have studied the magnetic order inside the superconducting phase of CeCoIn5 for fields along the [1 0 0] crystallographic direction using neutron diffraction. We find a spin-density wave order with an incommensurate modulation Q=(q,q,1/2) and q=0.45(1), which within our experimental uncertainty is indistinguishable from the spin-density wave found for fields applied along [1 -1 0]. The magnetic order is thus modulated along the lines of nodes of the d{x{2}-y{2}} superconducting order parameter, suggesting that it is driven by the electron nesting along the superconducting line nodes. We postulate that the onset of magnetic order leads to reconstruction of the superconducting gap function and a magnetically induced pair density wave.
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Lee HO, Kurita N, Ho PC, Condron CL, Klavins P, Kauzlarich SM, Maple MB, Movshovich R, Bauer ED, Thompson JD, Fisk Z. Weak coupling magnetism in Ce4Pt12Sn25: a small exchange limit in the Doniach phase diagram. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:065601. [PMID: 21389371 DOI: 10.1088/0953-8984/22/6/065601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Magnetic susceptibility, magnetization, specific heat, and electrical resistivity studies on single crystals of Ce4Pt12Sn25 reveal an antiferromagnetic transition at T(N) = 0.19 K, which develops from a paramagnetic state with a very large specific heat coefficient (C/T) of 14 J mol(-1) K(-2)-Ce just above T(N). On the basis of its crystal structure and these measurements, we argue that a weak magnetic exchange interaction in Ce4Pt12Sn25 is responsible for its low ordering temperature and a negligible Kondo-derived contribution to physical properties above T(N). The anomalous enhancement of specific heat above T(N) is suggested to be related, in part, to weak geometric frustration of f-moments in this compound.
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Bauer ED, Sidorov VA, Lee H, Kurita N, Ronning F, Movshovich R, Thompson JD. Coexistence of antiferromagnetism and superconductivity in CePt2ln7. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/200/1/012011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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