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In many physical situations in which many-body assemblies exist at temperature T, a characteristic quantum-mechanical time scale of approximately h/kBT can be identified in both theory and experiment, leading to speculation that it may be the shortest meaningful time in such circumstances. This behavior can be investigated by probing the scattering rate of electrons in a broad class of materials often referred to as "strongly correlated metals". It is clear that in some cases only electron-electron scattering can be its cause, while in others it arises from high-temperature scattering of electrons from quantized lattice vibrations, i.e., phonons. In metallic oxides, which are among the most studied materials, analysis of electrical transport does not satisfactorily identify the relevant scattering mechanism at "high" temperatures near room temperature. We therefore employ a contactless optical method to measure thermal diffusivity in two Ru-based layered perovskites, Sr3Ru2O7 and Sr2RuO4, and use the measurements to extract the dimensionless Lorenz ratio. By comparing our results to the literature data on both conventional and unconventional metals, we show how the analysis of high-temperature thermal transport can both give important insight into dominant scattering mechanisms and be offered as a stringent test of theories attempting to explain anomalous scattering. [ABSTRACT FROM AUTHOR]

A key question regarding the unconventional superconductivity of Sr2RuO4 remains whether the order parameter is single- or two-component. Under a hypothesis of two-component superconductivity, uniaxial pressure is expected to lift their degeneracy, resulting in a split transition. The most direct and fundamental probe of a split transition is heat capacity. Here, we report measurement of heat capacity of samples subject to large and highly homogeneous uniaxial pressure. We place an upper limit on the heat-capacity signature of any second transition of a few percent of that of the primary superconducting transition. The normalized jump in heat capacity, C=C, grows smoothly as a function of uniaxial pressure, favoring order parameters which are allowed to maximize in the same part of the Brillouin zone as the wellstudied van Hove singularity. Thanks to the high precision of our measurements, these findings place stringent constraints on theories of the superconductivity of Sr2RuO4. [ABSTRACT FROM AUTHOR]

To investigate the electronic state of CeRu2Al10, which exhibits an unusual antiferromagnetic order below TN = 27K, we measured the electrical resistivity, the transverse magnetoresistance (TMR), the Hall resistivity H, and the Shubnikov-de Haas (SdH) effect at low temperatures down to ~20mK and high magnetic fields up to 17.8 T. The temperature dependence of P at zero magnetic field exhibits a T 2 dependence below ~0.7 K, indicating a Fermi-liquid ground state. The TMR increases with increasing the magnetic field for a wide range of field directions except for particular directions around H // α, where the TMR shows a broad maximum at ~12 T. The field dependence of PH for H // α shows an evident increase around this field, suggesting a marked change in the mobility of carriers. The SdH effect measurements at temperatures lower than those of our previous work depicted the Fermi surface (FS) topology in more detail and confirmed the small size of the FS (SdH frequency F ~ 210 T). Relatively heavy cyclotron effective masses of up to 3.6m0 (m0: rest mass of electron) with a large anisotropy were observed despite the small carrier density. [ABSTRACT FROM AUTHOR]

Magnetic properties of an Yb-based semiconductor YbCuS2 with a zigzag chain of Yb3+ ions were studied. The Curie-Weiss behavior of the magnetic susceptibility χ(T) indicates antiferromagnetic interaction and an isolated Kramers doublet ground state with effective spin-1=2. Magnetic specific heat Cm=T exhibits a sharp peak at TO = 0.95 K, where the magnetic entropy is 20% of R ln 2, indicating strong magnetic fluctuations. In magnetic fields, TO is robust for B < 4 T, and it shifts to higher temperatures but reverses downward for B ≥ 7 T. Below TO, a magnetization plateau manifests itself at around 6 T which is followed by transitions at 9.1 and 15.6 T. The phase diagram suggests that nontrivial phases arise from magnetic frustration in the Yb zigzag chain. [ABSTRACT FROM AUTHOR]

Ln2Co12P7 (Ln = Y, Nd, and Sm) shows a ferromagnetic transition of Co magnetic moments approximately at 150 K. To know how the Nd and Sm moments interact with the Co moments, the magnetocaloric effect of Ln2Co12P7 was studied. For Ln = Nd and Sm, the value of the magnetic entropy change of Ln2Co12P7 is positive below 50 K and increases with decreasing temperature. This behavior of the magnetic entropy change indicates that the Ln moments interact antiferromagnetically with the Co moments. For Ln = Sm, this is the first report to verify the antiferromagnetic interaction with the Co moments. The value of the magnetic entropy change steeply drops below 12 K for Ln = Nd and 20 K for Ln = Sm at 5 T, suggesting antiferromagnetic transitions. [ABSTRACT FROM AUTHOR]

Hard X-ray photoemission studies are carried out to evaluate the electronic structure of iron-based superconductors BaFe2(As1-xPx)2 in a wide range of the P content 0 ≤ x ≤ 0.61. As x increases, the Fe 2p3/2 and Ba 3d5/2 core levels linearly shift to the higher and lower binding energy sides, respectively, while the anion core levels show no appreciable shifts. These results can be explained in terms of the Madelung potential and the change of the hybridization between the Fe 3d and the anion orbitals. The increase of the hybridization with x leads to an increase of the band width, which is consistent with the spectrum shift near the Fermi level. [ABSTRACT FROM AUTHOR]

We report measurements of resistance and ac magnetic susceptibility on FeSe single crystals under high pressure up to 27.2 kbar. The structural phase transition is quickly suppressed with pressure, and the associated anomaly is not seen above ~18 kbar. The superconducting transition temperature evolves nonmonotonically with pressure, showing a minimum at ~12 kbar. We find another anomaly at 21.2K at 11.6 kbar. This anomaly most likely corresponds to the antiferromagnetic phase transition found in μSR measurements [M. Bendele et al., Phys. Rev. Lett. 104, 087003 (2010)]. The antiferromagnetic and superconducting transition temperatures both increase with pressure up to ~25 kbar and then level off. The width of the superconducting transition anomalously broadens in the pressure range where the antiferromagnetism coexists. [ABSTRACT FROM AUTHOR]

Iron oxide photoelectrodes were prepared using pulsed laser deposition with hematite pellet as the target. The dependences of photocurrent density on post-annealing O2 pressure, thickness, heating temperature and surface morphology were investigated in detail. The photoelectrode properties were characterized using Raman spectroscopy, XPS, UV-vis absorption spectroscopy, SEM, current density and photoelectrochemical measurements. The a-Fe2O3 thin film of thickness 70 nm prepared using the SiO2 sphere template method with post-annealing under an O2 pressure of 160 Pa at 550 degC showed the highest photocurrent density (275 uA cm[?]2) under AM1.5 solar simulated light irradiation. [ABSTRACT FROM AUTHOR]