arXiv subjects

Tatsuya Honma

Publications and source records attributed to Tatsuya Honma.

7 recordsLinked to original sources

arXiv2026

Doping-induced evolution of the intrinsic hump and dip energies dependent on the sample fabrication conditions in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$

In oxygen-doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$, the spectra, as observed by tunneling or photoemission spectroscopic measurements, depend on the sample fabrication conditions, such as the temperature and pressure for fabricating the junction or surface. This implies that the hump and dip energies extracted from the spectra depend on the sample fabrication conditions. When the samples were fabricated at 4.2 K and/or under ultra-high vacuum (UHV), the hump energy exhibited a new step-like doping dependence and the dip energy followed the upper pseudo-gap line. As the fabrication conditions deteriorated, the hump and dip energies reproduced the previous results, in that the dip energy was significantly dependent on the sample, whereas the hump energy exhibited a smooth doping dependence. It can be concluded that the observations for the samples fabricated at 4.2 K and/or under UHV reflect the intrinsic bulk properties, whereas those for the samples fabricated under deteriorated conditions reflect degraded surface properties.

cond-mat.supr-con↗

arXiv2016

Anisotropic magnetoresistance of charge-density wave in $o$-TaS$_3$

We report the magnetoresistance of a charge-density wave (CDW) in $o$-TaS$_3$ whiskers at 4.2 K under a magnetic field up to 5.2 T. An anisotropic negative magnetoresistance is found in the nonlinear regime of current-voltage characteristics. The angle dependence of the magnetoresistance, studied by rotating the magnetic field upon the $c$-axis, exhibited a two-fold symmetry. The magnetoresistance amplitude exhibits maxima when the field is parallel to the $a$-axis, whereas it vanishes to the $b$-axis. The observed anisotropy may come from difference in interchain coupling of adjacent CDWs along the $a$- and $b$-axes. Comparison of the anisotropy to the scanning tunneling microscope image of CDWs allows us to provide a simple picture to explain the magnetoresistance in terms of delocalization of quantum interference of CDWs extending over the $b$-$c$ plane.

cond-mat.str-el↗

arXiv2015

Quantitative connection between the nanoscale electronic inhomogeneity and the pseudogap of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ superconductors

We have found a quantitative connection between the evolution of the inhomogeneous nanoscale electronic gaps (INSEG) state detected in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ by scanning tunneling microscopy/spectroscopy (STM/S) and the two universal, the upper and the lower, pseudogaps in high-temperature cuprate superconductors (HTCS). When the doping and temperature dependent INSEG map were analyzed by using our proposed hole-scale, we find that the two pseudogaps are connected to two specific coverages of the CuO$_2$ plane by INSEG: the 50\% and 100\% coverages of the CuO$_2$ planes by INSEG correspond to the upper and lower pseudogaps, respectively. This quantitative connection to the two pseudogaps indicates that the origin of the measured pseudogap energies and temperatures are intimately related to the geometrical coverage of the CuO$_2$ planes by the INSEG state. We find that INSEG and superconductivity coexist in the underdoped to the overdoped regimes. We suggest that pseudogap states are microscopically inhomogeneous and 100\% coverage of the CuO$_2$ planes by the INSEG is a necessary condition for the high-$T_c$ superconductivity.

cond-mat.supr-con↗

arXiv2011

Energy-Dependent Enhancement of the Electron-Coupling Spectrum of the Underdoped Bi2Sr2CaCu2O8+d Superconductor

We have determined the electron-coupling spectrum of superconducting Bi2Sr2CaCu2O8+d from high-resolution angle-resolved photoemission spectra by two deconvolution-free robust methods. As hole concentration decreases, the coupling spectral weight at low energies ~<15 meV shows a twofold and nearly band-independent enhancement, while that around ~65 meV increases moderately, and that in ~>130 meV decreases leading to a crossover of dominant coupling excitation between them. Our results suggest the competition among multiple screening effects, and provide important clues to the source of sufficiently strong low-energy coupling, λLE ~ 1, in underdoped system.

cond-mat.supr-con↗

arXiv2010

Universal scaling of c-axis dc conductivity for the underdoped hightemperature cuprate superconductors

Coexistence of the "metallic-like" in-plane and the "semiconducting-like" out-of-plane (caxis) dc conductivities (σc), generating a huge anisotropy in the underdoped hightemperature cuprate superconductors (HTCS), defies our current understanding of metal. In this report we present an intrinsic doping dependence of σc. We find that the σc for the underdoped HTCS is universally scaled to the σc at the optimal doped-hole concentration. The universal scaling behavior suggests that there are three intrinsic processes contribute to σc: (i) the doping-dependent-activated gap; (ii) the exponential doping dependences and (iii) the tunneling between adjacent CuO2 block layers. They are the essential underlying characteristics of the c-axis transport for all HTCSs.

cond-mat.supr-con↗

arXiv2009

Comparison of the Hole Concentration determined by Transport Measurement for the Hole-doped Cuprate Superconductors

We have compared the hole concentration ($P_{pl}$) determined by hole-scale based on the thermoelectric power at RT ($S^{290}$) to the hole concentrations ($P$) determined by two popular hole-scales based on the superconducting critical temperature ($T_c$) and Hall coefficient ($R_H$). While the hole concentrations based on different hole-scales are different, we show that when the $P_{pl}$ is divided by either the effective unit cell volume ($V_{euc}$) which is the unit-cell volume per one CuO$_2$ plane or the optimal hole concentration ($P_{pl}^{opt}$) we can find some correlation between $P_{pl}$ and $P$. That is, the normalized $T_c$ ($T_c$ / $T_c$($P_{pl}^{opt}$)) and the Hall number (1/$eR_H$) are well scaled with $P_{pl}$ / $P_{pl}^{opt}$ and $P_{pl}$ / $V_{euc}$, respectively. We find that the $P_{pl}$-scale can map to and reproduce the other two hole scales if proper dimensionality and normalization are taken into account but not vice versa.

cond-mat.supr-con↗

arXiv2006

Planar hole-doping concentration and effective three-dimensional hole-doping concentration for single-layer high-$T_c$ superconductors

We propose that physical properties for the high temperature superconductors can be addressed by either a two-dimensional planar hole-doping concentration ($P_{pl}$) or an effective three-dimentional hole-doping concentration ($P_{3D}$). We find that superconducting transition temperature ($T_c$) exhibits a universal dome-shaped behavior in the $T_c$ $vs.$ $P_{3D}$ plot with a universal optimal doping concentration at $P_{3D}$ $\sim$ 1.6 $\times$ 10$^{21}$ cm$^{-3}$ for the single-layer high temperature superconductors.

cond-mat.supr-con↗