12,866 research outputs found

    Anomalous Nernst and Hall effects in magnetized platinum and palladium

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    We study the anomalous Nernst effect (ANE) and anomalous Hall effect (AHE) in proximity-induced ferromagnetic palladium and platinum which is widely used in spintronics, within the Berry phase formalism based on the relativistic band structure calculations. We find that both the anomalous Hall (σxyA\sigma_{xy}^A) and Nernst (αxyA\alpha_{xy}^A) conductivities can be related to the spin Hall conductivity (σxyS\sigma_{xy}^S) and band exchange-splitting (Δex\Delta_{ex}) by relations σxyA=ΔexeσxyS(EF)\sigma_{xy}^A =\Delta_{ex}\frac{e}{\hbar}\sigma_{xy}^S(E_F)' and αxyA=π23kB2TΔexσxys(μ)"\alpha_{xy}^A = -\frac{\pi^2}{3}\frac{k_B^2T\Delta_{ex}}{\hbar}\sigma_{xy}^s(\mu)", respectively. In particular, these relations would predict that the σxyA\sigma_{xy}^A in the magnetized Pt (Pd) would be positive (negative) since the σxyS(EF)\sigma_{xy}^S(E_F)' is positive (negative). Furthermore, both σxyA\sigma_{xy}^A and αxyA\alpha_{xy}^A are approximately proportional to the induced spin magnetic moment (msm_s) because the Δex\Delta_{ex} is a linear function of msm_s. Using the reported msm_s in the magnetized Pt and Pd, we predict that the intrinsic anomalous Nernst conductivity (ANC) in the magnetic platinum and palladium would be gigantic, being up to ten times larger than, e.g., iron, while the intrinsic anomalous Hall conductivity (AHC) would also be significant.Comment: Accepted for publication in the Physical Review

    Context effects in inflation surveys: The influence of additional information and prior questions

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    Context effects are known to affect responses to surveys. We report effects of information and task contexts in surveys of inflation expectations. Information context refers to contextual information about earlier inflation rates or other economic indicators. Task context refers to judgement tasks performed prior to the inflation judgement task under consideration. In three experiments, we show that contextual information improves judgement accuracy. As this information is given in expert, but not in lay surveys, its provision may partly explain why expert judgements are superior to those of lay people. In both expert and lay surveys, respondents make inflation judgements in the context of already having made other inflation judgements. We show that when different groups of people make inflation judgements either for the current or for the upcoming year, their judgements do not differ. However, when the same people make judgements for both the current and the upcoming years, the latter are significantly higher than the former, perhaps because people expect inflation to increase over time

    Are lay expectations of inflation based on recall of specific prices? If so, how and under what conditions?

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    In 2019 when inflation was low and stable, we compared people's direct estimates of inflation with indirect estimates obtained by averaging their estimates of price changes in all 12 product categories on which the consumer price index is based. Indirect estimates were much higher than direct ones and the two types of estimate were uncorrelated. This is consistent with a price-free model in which direct estimates are not based on recall of prices but are determined by other information such as media reports. In May 2022 when inflation was high, expected to rise in the short-term, but highly unpredictable in the longer term, we found that direct and indirect estimates were very similar and highly correlated. This is consistent with a price-recall model in which a representative set of prices is used to estimate overall inflation. Finally, in September 2022 when inflation was fairly stable except for certain product categories (food) where prices were rising rapidly, we found that results were consistent with a third approach, the price-salience model; overall estimates of inflation are selectively influenced by price rises in those product categories where they are particularly high. People's strategy for estimating inflation appears adapted to the prevailing inflation environment

    Carrier-envelope phase dependence in single-cycle laser pulse propagation with the inclusion of counter-rotating terms

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    We focus on the propagation properties of a single-cycle laser pulse through a two-level medium by numerically solving the full-wave Maxwell-Bloch equations. The counter-rotating terms in the spontaneous emission damping are included such that the equations of motion are slightly different from the conventional Bloch equations. The counter-rotating terms can considerably suppress the broadening of the pulse envelope and the decrease of the group velocity rooted from dispersion. Furthermore, for incident single-cycle pulses with envelope area 4π\pi, the time-delay of the generated soliton pulse from the main pulse depends crucially on the carrier-envelope phase of the incident pulse. This can be utilized to determine the carrier-envelope phase of the single-cycle laser pulse.Comment: 6 pages, 5 figure

    Partial entropy in finite-temperature phase transitions

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    It is shown that the von Neumann entropy, a measure of quantum entanglement, does have its classical counterpart in thermodynamic systems, which we call partial entropy. Close to the critical temperature the partial entropy shows perfect finite-size scaling behavior even for quite small system sizes. This provides a powerful tool to quantify finite-temperature phase transitions as demonstrated on the classical Ising model on a square lattice and the ferromagnetic Heisenberg model on a cubic lattice.Comment: 4 pages, 6 figures, Revised versio

    The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio

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    The A1ΠX1Σ+\textrm{A}^1\Pi-\textrm{X}^1\Sigma^+ band system of carbon monoxide, which has been detected in six highly redshifted galaxies (z=1.62.7z=1.6-2.7), is identified as a novel probe method to search for possible variations of the proton-electron mass ratio (μ\mu) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X (vv,0) bands for v=09v=0-9 have been determined at an accuracy of Δλ/λ=1.5×107\Delta\lambda/\lambda=1.5 \times 10^{-7} through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0) bands, two-photon Doppler-free laser spectroscopy has been applied at the 3×1083 \times 10^{-8} accuracy level, verifying the absorption data. Sensitivity coefficients KμK_{\mu} for a varying μ\mu have been calculated for the CO A-X bands, so that an operational method results to search for μ\mu-variation.Comment: 7 pages (main article), 3 figures, includes supplementary materia

    Compression of Atomic Phase Space Using an Asymmetric One-Way Barrier

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    We show how to construct asymmetric optical barriers for atoms. These barriers can be used to compress phase space of a sample by creating a confined region in space where atoms can accumulate with heating at the single photon recoil level. We illustrate our method with a simple two-level model and then show how it can be applied to more realistic multi-level atoms

    On the transport and thermodynamic properties of quasi-two-dimensional purple bronzes A0.9_{0.9}Mo6_6O17_{17} (A=Na, K)

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    We report a comparative study of the specific heat, electrical resistivity and thermal conductivity of the quasi-two-dimensional purple bronzes Na0.9_{0.9}Mo6_6O17_{17} and K0.9_{0.9}Mo6_6O17_{17}, with special emphasis on the behavior near their respective charge-density-wave transition temperatures TPT_P. The contrasting behavior of both the transport and the thermodynamic properties near TPT_P is argued to arise predominantly from the different levels of intrinsic disorder in the two systems. A significant proportion of the enhancement of the thermal conductivity above TPT_P in Na0.9_{0.9}Mo6_6O17_{17}, and to a lesser extent in K0.9_{0.9}Mo6_6O17_{17}, is attributed to the emergence of phason excitations.Comment: 8 pages, 6 figures, To appear in Physical Review
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