51
|
Luo H, Gibson Q, Krizan J, Cava RJ. Ferromagnetism in Mn-doped Sb(2)Te. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:206002. [PMID: 24786568 DOI: 10.1088/0953-8984/26/20/206002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report that Sb2Te, a natural superlattice phase consisting of two elemental Sb2 layers interleaved with single Sb2Te3 layers, becomes ferromagnetic at low temperatures on doping with small percentages of Mn. Ferromagnetism appears for Mn concentrations as low as Sb1.98Mn0.02Te, where a ferromagnetic Tc of ~8.6 K is observed. Tc decreases with increasing Mn content in the stoichiometric materials but increases with increasing Te excess in materials of the type Sb1.93-yMn0.07Te1+y, starting at ~3 K at y = 0 and reaching a Tc of ~8.9 K at y = 0.06.
Collapse
|
52
|
Morris CM, Valdés Aguilar R, Ghosh A, Koohpayeh SM, Krizan J, Cava RJ, Tchernyshyov O, McQueen TM, Armitage NP. Hierarchy of bound states in the one-dimensional ferromagnetic Ising chain CoNb2O6 investigated by high-resolution time-domain terahertz spectroscopy. PHYSICAL REVIEW LETTERS 2014; 112:137403. [PMID: 24745454 DOI: 10.1103/physrevlett.112.137403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Indexed: 06/03/2023]
Abstract
Kink bound states in the one-dimensional ferromagnetic Ising chain compound CoNb2O6 have been studied using high-resolution time-domain terahertz spectroscopy in zero applied magnetic field. When magnetic order develops at low temperature, nine bound states of kinks become visible. Their energies can be modeled exceedingly well by the Airy function solutions to a 1D Schrödinger equation with a linear confining potential. This sequence of bound states terminates at a threshold energy near 2 times the energy of the lowest bound state. Above this energy scale we observe a broad feature consistent with the onset of the two particle continuum. At energies just below this threshold we observe a prominent excitation that we interpret as a novel bound state of bound states--two pairs of kinks on neighboring chains.
Collapse
|
53
|
Ali MN, Gibson Q, Jeon S, Zhou BB, Yazdani A, Cava RJ. The Crystal and Electronic Structures of Cd3As2, the Three-Dimensional Electronic Analogue of Graphene. Inorg Chem 2014; 53:4062-7. [DOI: 10.1021/ic403163d] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
54
|
Fennell T, Kenzelmann M, Roessli B, Mutka H, Ollivier J, Ruminy M, Stuhr U, Zaharko O, Bovo L, Cervellino A, Haas MK, Cava RJ. Magnetoelastic excitations in the pyrochlore spin liquid Tb2Ti2O7. PHYSICAL REVIEW LETTERS 2014; 112:017203. [PMID: 24483925 DOI: 10.1103/physrevlett.112.017203] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Indexed: 06/03/2023]
Abstract
At low temperatures, Tb2Ti2O7 enters a spin liquid state, despite expectations of magnetic order and/or a structural distortion. Using neutron scattering, we have discovered that in this spin liquid state an excited crystal field level is coupled to a transverse acoustic phonon, forming a hybrid excitation. Magnetic and phononlike branches with identical dispersion relations can be identified, and the hybridization vanishes in the paramagnetic state. We suggest that Tb2Ti2O7 is aptly named a "magnetoelastic spin liquid" and that the hybridization of the excitations suppresses both magnetic ordering and the structural distortion. The spin liquid phase of Tb2Ti2O7 can now be regarded as a Coulomb phase with propagating bosonic spin excitations.
Collapse
|
55
|
Seibel EM, Roudebush JH, Wu H, Huang Q, Ali MN, Ji H, Cava RJ. Structure and Magnetic Properties of the α-NaFeO2-Type Honeycomb Compound Na3Ni2BiO6. Inorg Chem 2013; 52:13605-11. [DOI: 10.1021/ic402131e] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
56
|
Wray LA, Xu S, Neupane M, Fedorov AV, Hor YS, Cava RJ, Hasan MZ. Chemically gated electronic structure of a superconducting doped topological insulator system. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/449/1/012037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
57
|
Roudebush JH, Andersen NH, Ramlau R, Garlea VO, Toft-Petersen R, Norby P, Schneider R, Hay JN, Cava RJ. Structure and Magnetic Properties of Cu3Ni2SbO6 and Cu3Co2SbO6 Delafossites with Honeycomb Lattices. Inorg Chem 2013; 52:6083-95. [DOI: 10.1021/ic400415h] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
58
|
Hirai D, Bremholm M, Allred JM, Krizan J, Schoop LM, Huang Q, Tao J, Cava RJ. Spontaneous formation of zigzag chains at the metal-insulator transition in the β-pyrochlore CsW2O6. PHYSICAL REVIEW LETTERS 2013; 110:166402. [PMID: 23679626 DOI: 10.1103/physrevlett.110.166402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Indexed: 06/02/2023]
Abstract
A paramagnetic metal to nonmagnetic insulator transition at T(MIT)=210 K is reported for the β-pyrochlore oxide CsW(2)O(6), accompanied by a first order structural transition that creates <110> oriented chains in the pyrochlore lattice. Comparison of CsW(2)O(6), which has 1 electron per 2 W sites, to the fully d(0) analog CsTaWO(6) shows that the transitions are electronically driven. Corefinement of high resolution synchrotron x-ray and neutron diffraction data shows that the structural distortion that creates the W chains cannot be attributed to simple charge or orbital ordering. Density functional theory calculations suggest that the phase transition is driven by a sharply peaked electronic density of states near the Fermi energy in the cubic β-pyrochlore phase. A further electronic instability is required to create the insulating ground state.
Collapse
|
59
|
Schoop LM, Müchler L, Felser C, Cava RJ. Lone Pair Effect, Structural Distortions, and Potential for Superconductivity in Tl Perovskites. Inorg Chem 2013; 52:5479-83. [DOI: 10.1021/ic400381g] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
60
|
Kumar M, Dutton SE, Cava RJ, Soos ZG. Spin-flop and antiferromagnetic phases of the ferromagnetic half-twist ladder compounds Ba3Cu3In4O12 and Ba3Cu3Sc4O12. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:136004. [PMID: 23462552 DOI: 10.1088/0953-8984/25/13/136004] [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 title compounds have dominant ferromagnetic exchange interactions within one-dimensional (1D) half-twist ladders of s = 1/2 Cu(2+) ions and antiferromagnetic (AFM) interactions between ladders, leading to ordered 3D phases at temperatures below 20 K. Here we show that a microscopic 1D model of the paramagnetic (PM) phase combined with a phenomenological model based on sublattice magnetization describes the observed temperature and field dependent magnetism. The model identifies AFM, spin-flop and PM phases whose boundaries have sharp features in the experimental magnetization M(T,H) and specific heat C(P)(T,H). Exact diagonalization of the 1D model, possible for 24 spins due to special structural features of half-twist ladders, yields the magnetization and spin susceptibility of the PM phase. AFM interactions between ladders are included at the mean-field level using the field, H(AF), obtained from modelling the ordered phases. Isotropic exchange J1 =- 135 K and g-tensor g = 2.1 within ladders, plus exchange and anisotropy fields H(AF) and H(A), describe the ordered phases and are almost quantitative for the PM phase.
Collapse
|
61
|
Klimczuk T, Sidorov VA, Szajek A, Werwiński M, Kimber SAJ, Kozub AL, Safarik D, Thompson JD, Cava RJ. Structure and paramagnetism in weakly correlated Y8Co5. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:125701. [PMID: 23448945 DOI: 10.1088/0953-8984/25/12/125701] [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
We report the basic physical properties of monoclinic Y8Co5 determined by means of magnetic susceptibility, electrical resistivity, and specific heat measurements. The crystal structure of Y8Co5 is monoclinic (P2(1)/c) with lattice parameters a = 7.0582(6) Å, b = 7.2894(6) Å, c = 24.2234(19) Å, and β = 102.112(6)° as refined by using synchrotron powder x-ray diffraction data. The compound shows temperature independent paramagnetism with χ0 = 2.1 × 10(-3) emu mol(-1) and Sommerfeld parameter γ = 63 mJ mol(-1) K(-2). The calculated Wilson ratio for Y8Co5, R(W) = 1.4, is close to that expected for a free electron gas R(W) = 1. Low temperature resistivity under high pressure does not reveal superconductivity in this compound down to 1.2 K, up to hydrostatic pressures of 5.56 GPa. Band structure calculations (full-potential linearized augmented plane wave, FP-LAPW) derive the Stoner exchange interaction parameter S = 0.24, excluding magnetic behavior for Y8Co5.
Collapse
|
62
|
Zhou T, Koutroulakis G, Lodico J, Ni N, Thompson JD, Cava RJ, Brown SE. Antiferromagnetic order in Ca10(Pt3As8)(Fe2As2)5 observed by 75As NMR. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:122201. [PMID: 23420320 DOI: 10.1088/0953-8984/25/12/122201] [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
75As nuclear magnetic resonance (NMR) measurements carried out on underdoped, non-superconducting Ca10(Pt3As8)(Fe2As2)5 reveal physical properties that are similar but not identical to 122 superconductor parent compounds such as BaFeAs. Results from the single crystal study indicate a phase transition to an antiferromagnetic (AF) state on cooling through T ~ 100 K, albeit nonuniformly. Specifically, the NMR lineshape reflects the presence of staggered hyperfine fields on the As sites associated with a striped AF order. The variation of the internal hyperfine field with temperature suggests that the phase transition to the AF state is discontinuous, and therefore likely coincident with the structural transition inferred from transport experiments.
Collapse
|
63
|
LaForge AD, Pulido SH, Cava RJ, Chan BC, Ramirez AP. Quasispin glass in a geometrically frustrated magnet. PHYSICAL REVIEW LETTERS 2013; 110:017203. [PMID: 23383834 DOI: 10.1103/physrevlett.110.017203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Indexed: 06/01/2023]
Abstract
The spin glass state in the spinel ZnCr(2(1-x))Ga(2x)O(4) is studied with magnetization and specific heat for x < 0.05. The freezing temperature is independent of disorder, despite a two-level-like density of states that varies linearly with x. This relationship implies the energy scale for freezing is independent of disorder, in contrast to mean field theories of spin glass. We suggest that the degrees of freedom are shielded spin vacancies, quasispins, which interact via an emergent long-range force mediated by the frustrated spin background.
Collapse
|
64
|
Qu DX, Hor YS, Cava RJ. Quantum oscillations in magnetothermopower measurements of the topological insulator Bi2Te3. PHYSICAL REVIEW LETTERS 2012; 109:246602. [PMID: 23368356 DOI: 10.1103/physrevlett.109.246602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Indexed: 06/01/2023]
Abstract
We report the magnetothermopower measurements of the nonmetallic topological insulator Bi(2)Te(3) in magnetic fields up to 35 T. Quantum oscillations arising from surface states are observed in both thermoelectric and conductivity tensors. The inferred surface thermopower has a peak magnitude ~1 mV/K possibly as a result of surface electron and bulk phonon interaction. At the n = 1 Landau level, we resolve additional quantum oscillations signaling Landau sublevels.
Collapse
|
65
|
Bremholm M, Dutton SE, Stephens PW, Cava RJ. Discovery of novel post-perovskites by high-pressure methods. Acta Crystallogr A 2012. [DOI: 10.1107/s0108767312098972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
66
|
Fennell T, Kenzelmann M, Roessli B, Haas MK, Cava RJ. Power-law spin correlations in the pyrochlore antiferromagnet Tb(2)Ti(2)O(7). PHYSICAL REVIEW LETTERS 2012; 109:017201. [PMID: 23031127 DOI: 10.1103/physrevlett.109.017201] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 03/19/2012] [Indexed: 06/01/2023]
Abstract
We investigate the low-temperature state of the rare-earth pyrochlore Tb(2)Ti(2)O(7) using polarized neutron scattering. Tb(2)Ti(2)O(7) is often described as an antiferromagnetic spin liquid with spin correlations extending over lengths comparable to individual tetrahedra of the pyrochlore lattice. We confirm this picture at 20 K but find that at 0.05 K the data contain evidence of pinch-point scattering, suggesting that the low temperature state of Tb(2)Ti(2)O(7) has power-law spin correlations.
Collapse
|
67
|
Dutton SE, Kumar M, Mourigal M, Soos ZG, Wen JJ, Broholm CL, Andersen NH, Huang Q, Zbiri M, Toft-Petersen R, Cava RJ. Quantum spin liquid in frustrated one-dimensional LiCuSbO4. PHYSICAL REVIEW LETTERS 2012; 108:187206. [PMID: 22681114 DOI: 10.1103/physrevlett.108.187206] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Indexed: 06/01/2023]
Abstract
A quantum magnet, LiCuSbO4, with chains of edge-sharing spin-1/2 CuO6 octahedra is reported. While short-range order is observed for T<10 K, no zero-field phase transition or spin freezing occurs down to 100 mK. Specific heat indicates a distinct high-field phase near the 12 T saturation field. Neutron scattering shows incommensurate spin correlations with q=(0.47±0.01)π/a and places an upper limit of 70 μeV on any spin gap. Exact diagonalization of 16-spin easy-plane spin-1/2 chains with competing ferro- and antiferromagnetic interactions (J1=-75 K, J2=34 K) accounts for the T>2 K data.
Collapse
|
68
|
Dutton SE, Kumar M, Soos ZG, Broholm CL, Cava RJ. Dominant ferromagnetism in the spin-1/2 half-twist ladder 334 compounds, Ba3Cu3In4O12 and Ba3Cu3Sc4O12. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:166001. [PMID: 22446062 DOI: 10.1088/0953-8984/24/16/166001] [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
The magnetic properties of polycrystalline samples of Ba(3)Cu(3)In(4)O(12) (In-334) and Ba(3)Cu(3)Sc(4)O(12) (Sc-334) are reported. Both 334 phases have a structure derived from perovskite, with CuO(4) squares interconnected to form half-twist ladders along the c-axis. The Cu-O-Cu angles, ~90°, and the positive Weiss temperatures indicate the presence of significant ferromagnetic (FM) interactions along the Cu ladders. At low temperatures, T < 20 K, sharp transitions in the magnetic susceptibility and heat capacity measurements indicate three-dimensional (3D) antiferromagnetic (AFM) ordering at T(N). T(N) is suppressed on application of a field and a complex magnetic phase diagram with three distinct magnetic regimes below the upper critical field can be inferred from our measurements. The magnetic interactions are discussed in relation to a modified spin-1/2 FM-AFM model and the 334 half-twist ladder is compared to other two-rung ladder spin-1/2 systems.
Collapse
|
69
|
Bremholm M, Yim CK, Hirai D, Climent-Pascual E, Xu Q, Zandbergen HW, Ali MN, Cava RJ. Destabilization of the 6H-SrIrO3 polymorph through partial substitution of zinc and lithium. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32558f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
70
|
Dutton SE, Hanson ED, Broholm CL, Slusky JS, Cava RJ. Magnetic properties of hole-doped SCGO, SrCr(8)Ga(4-x)M(x)O(19) (M = Zn, Mg, Cu). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:386001. [PMID: 21891853 DOI: 10.1088/0953-8984/23/38/386001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report changes in the magnetic properties of hole-doped SCGO, SrCr8Ga4O19, induced by replacing non-magnetic Ga3+ with both non-magnetic (Mg2+ and Zn2+) and magnetic (Cu2+) cations. The resulting solid solutions, SrCr(8)Ga(4-x)M(x)O(19) (M = Zn, Mg, Cu) have been studied by x-ray diffraction and magnetic susceptibility measurements. For all cases, at least 10% of Ga can be replaced by divalent cations resulting in oxidation of ≥5% of the Cr3+ d3 to Cr4+ (d2). The hole doping results in an increase in ferromagnetic interactions and reduces the magnetic frustration. In the SrCr(8)Ga(4-x)Cu(x)O(19) series an enhancement of the spin-glass-like transition is observed, T(f)∼ 6 K, which we ascribe to the magnetic nature of the Cu2+ (d9) dopant.
Collapse
|
71
|
Dutton SE, Climent-Pascual E, Stephens PW, Hodges JP, Huq A, Broholm CL, Cava RJ. Helical magnetism and structural anomalies in triangular lattice α-SrCr2O4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:246005. [PMID: 21625037 DOI: 10.1088/0953-8984/23/24/246005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
α-SrCr(2)O(4) has a triangular planar lattice of d(3) Cr(3+) made from edge sharing CrO(6) octahedra; the plane shows a very small orthorhombic distortion from hexagonal symmetry. With a Weiss temperature of - 596 K and a three-dimensional magnetic ordering temperature of 43 K, the magnetic system is quasi-two-dimensional and frustrated. Neutron powder diffraction shows that the ordered state is an incommensurate helical magnet, with an in-plane propagation vector of k = (0, 0.3217(8), 0). Temperature dependent synchrotron powder diffraction characterization of the structure shows an increase in the inter-plane spacing on cooling below 100 K and an inflection in the cell parameters at the magnetic ordering temperature. These anomalies indicate the presence of a moderate degree of magnetostructural coupling.
Collapse
|
72
|
Checkelsky JG, Hor YS, Cava RJ, Ong NP. Bulk band gap and surface state conduction observed in voltage-tuned crystals of the topological insulator Bi2Se3. PHYSICAL REVIEW LETTERS 2011; 106:196801. [PMID: 21668185 DOI: 10.1103/physrevlett.106.196801] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 04/01/2011] [Indexed: 05/13/2023]
Abstract
We report a transport study of exfoliated few monolayer crystals of topological insulator Bi2Se3 in an electric field effect geometry. By doping the bulk crystals with Ca, we are able to fabricate devices with sufficiently low bulk carrier density to change the sign of the Hall density with the gate voltage V(g). We find that the temperature T and magnetic field dependent transport properties in the vicinity of this V(g) can be explained by a bulk channel with activation gap of approximately 50 meV and a relatively high-mobility metallic channel that dominates at low T. The conductance (approximately 2×7e2/h), weak antilocalization, and metallic resistance-temperature profile of the latter lead us to identify it with the protected surface state. The relative smallness of the observed gap implies limitations for electric field effect topological insulator devices at room temperature.
Collapse
|
73
|
Xu SY, Xia Y, Wray LA, Jia S, Meier F, Dil JH, Osterwalder J, Slomski B, Bansil A, Lin H, Cava RJ, Hasan MZ. Topological Phase Transition and Texture Inversion in a Tunable Topological Insulator. Science 2011; 332:560-4. [DOI: 10.1126/science.1201607] [Citation(s) in RCA: 374] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
74
|
Graebner JE, Schneemeyer LF, Cava RJ, Waszczak JV, Rietman EA. Thermal Conductivity of Single-Crystal and Sintered RBa2Cu3O7 at low Temperatures. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-99-745] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTThe thermal conductivity k of micro-twinned single crystals of YBa2Cu3O7 and HoBa2Cu3O7 and a sintered sample of YBa2Cu3O7 has been measured for temperatures 0.03<T<5K. For the single crystals, k is small and varies as T1.8-1.9 This behavior resembles k for glassy insulators except for the lack of a plateau above IK. It is concluded that the thermal carriers are phonons with their mean free path limited by resonant scattering from tunneling entities, as in glasses. Suggestions for the location of tunneling systems are given. For the sinter, k is still smaller but does not follow a power law T-dependence. It is similar to other sintered ceramics with the same particle size, where the phonon mean free path is dominated by Rayleigh scattering from the particles. This strong scattering from the microstructure presumably masks the scattering from TS within each particle.
Collapse
|
75
|
Ramirez AP, Cava RJ, Espinosa GP, Remeika JP, Batlogg B, Zahurak S, Rietman EA. Specific Heat Linear Term in YBa2Cu3O7−x and a Survey of Related Compounds. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-99-459] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTWe have measured the specific heat, C, in the temperature range 0.3 to 20K and in magnetic fields up to 12 Tesla of several compounds related to the high-Tc superconductors. The linear term in C for YBa2Cu3O7−x is only weakly dependent on oxygen concentration in the range 0 ≤ × ≤ 0.7. The linear term in C changes by less than 10% at 10 Tesla for La1.98Sr.02CuO4, whereas for YBa2Cu3O7−x it is obscured by additional field-dependent structure. Magnetic ordering anomalies are observed in YBa2Cu2O5 at 10.6 K and in BaCuO2+6 at 9.3 K.
Collapse
|