In-plane thermoelectric properties of heavily underdoped high-temperature superconductor Bi₂Sr₂CaCu₂O_8+δ

Abstract

The effect of a magnetic field component parallel to the superconducting layers on longitudinal Josephson plasma oscillations in the layered high temperature superconductor Bi2Sr2CaCu2O 8+δ is shown to depend on the thermodynamic state of the underlying vortex lattice. Whereas the parallel magnetic field component depresses the Josephson Plasma Resonance (JPR) frequency in the vortex solid phase, it may enhance it in the vortex liquid. There is a close correlation between the behavior of microwave absorption near the JPR frequency and the effectiveness of pancake vortex pinning, with the enhancement of the plasma resonance frequency occurring in the absence of pinning, at high temperature close to the vortex melting line. An interpretation is proposed in terms of the attraction between pancake vortices and Josephson vortices, apparently also present in the vortex liquid state.

Investigation of the thermoelectric properties of La2CuO4 ceramics with the addition of Ag

“…For a specific temperature, the ZT value first increases and then decreases as the Ag dose rises. For these samples, the maximum ZT value is 0.018 at 308 K for LCOA5, which is similar to a recently reported result of 0.025 at 210 K for single crystal Bi 2 (Sr,La) 2 CaCu 2 O 8 þ δ [19], but it is much smaller than the value 0.6 reported for YBa 2 Cu 3 O 7À δ [18]. It should be noticed that every TE parameter of the pure La 2 CuO 4 sample measured in this work is close to the results reported in previous work on La 2 CuO 4 [15,17,36,37].…”

“…As part of the studies of their intrinsic properties, their Seebeck coefficients were measured [14], and several of them were found to have large Seebeck coefficients [15][16][17]. YBa 2 Cu 3 O 7À δ , to best of our knowledge, has the highest reported ZT value (0.6 at 300 K) of the high-temperature Cu-based superconductors [18], although this result requires further verification [19]. La 2 CuO 4 has a large Seebeck coefficient of 340 μV/K at room temperature [15,17], and several groups have investigated the TE properties of La 2 CuO 4 doped with various elements [20][21][22].…”

Research Update: Oxide thermoelectrics: Beyond the conventional design rules

“…Thus the electrons and holes can be equally excited in the Cu oxides, making the thermopower smaller in magnitude. 38 The solid curve represents α K for a quarter-filled triangular lattice. 34 In order to fit the data with the curve, we employed a value of 500 K for the hopping parameter t. The curve is semi-qualitatively consistent with the observed α ⊥ for the layered Co oxide.…”

High-Temperature Thermoelectricity in LaNiO3–La2CuO4 Heterostructures

“…In this study, lanthanum cuprate La 2 CuO 4 (LCO) and lanthanum nickelate LaNiO 3 (LNO) were chosen as constituents of the layered structure. It is noteworthy that the TE properties of LCO have been investigated over the last two decades, and several groups have reported large positive Seebeck coefficients. − On the other hand, the Seebeck coefficient of the LNO compound is small and negative . Another difference is the oxygen-exchange dynamics in these two oxides.…”