2,336 research outputs found

### Fermi surface and superconductivity in low-density high-mobility {\delta}-doped SrTiO3

The electronic structure of low-density n-type SrTiO3 delta-doped
heterostructures is investigated by angular dependent Shubnikov-de Haas
oscillations. In addition to a controllable crossover from a three- to
two-dimensional Fermi surface, clear beating patterns for decreasing dopant
layer thicknesses are found. These indicate the lifting of the degeneracy of
the conduction band due to subband quantization in the two-dimensional limit.
Analysis of the temperature-dependent oscillations shows that similar effective
masses are found for all components, associated with the splitting of the light
electron pocket. The dimensionality crossover in the superconducting state is
found to be distinct from the normal state, resulting in a rich phase diagram
as a function of dopant layer thickness.Comment: 4 pages, 5 figures, submitted for publicatio

### Electronic Phase Diagram of High-T_c Cuprate Superconductors from a Mapping of the In-Plane Resistivity Curvature

We propose that Resistivity Curvature Mapping (RCM) based on the in-plane
resistivity data is a useful way to objectively draw an electronic phase
diagrams of high-T_c cuprates, where various crossovers are important. In
particular, the pseudogap crossover line can be conveniently determined by RCM.
We show experimental phase diagrams obtained by RCM for
Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta}, La_{2-x}Sr_{x}CuO_{4}, and
YBa_{2}Cu_{3}O_{y}, and demonstrate the universal nature of the pseudogap
crossover. Intriguingly, the electronic crossover near optimum doping depicted
by RCM appears to occur rather abruptly, suggesting that the quantum critical
regime, if exists, must be very narrow.Comment: 4 pages, 3 color figures, final version accepted for publication in
Phys. Rev. Let

### Thermal Conductivity of Pr_{1.3-x}La_{0.7}Ce_xCuO_4 Single Crystals and Signatures of Stripes in an Electron-Doped Cuprate

It was recently demonstrated that the anisotropic phonon heat transport
behavior is a good probe of the stripe formation in La_{2-x}Sr_xCuO_4 (LSCO)
[X. F. Sun {\it et al.}, Phys. Rev. B {\bf 67}, 104503 (2003)]. Using this
probe, we examined an electron-doped cuprate Pr_{1.3-x}La_{0.7}Ce_xCuO_4
(PLCCO) and found that essentially the same features as those in LSCO are
observed. Moreover, the in-plane resistivity \rho_{ab} of lightly-doped PLCCO
shows metallic behavior (d\rho_{ab}/dT > 0) in the N\'eel ordered state with a
mobility comparable to that in LSCO. It is discussed that these peculiar
properties in common with LSCO signify the existence of stripes in
electron-doped cuprates.Comment: 4 pages, 4 figures, revised version accepted for publication in Phys.
Rev. Let

### Evolution of the Hall Coefficient and the Peculiar Electronic Structure of the Cuprate Superconductors

Although the Hall coefficient R_H is an informative transport property of
metals and semiconductors, its meaning in the cuprate superconductors has been
ambiguous because of its unusual characteristics. Here we show that a
systematic study of R_H in La_{2-x}Sr_{x}CuO_{4} single crystals over a wide
doping range establishes a qualitative understanding of its peculiar evolution,
which turns out to reflect a two-component nature of the electronic structure
caused by an unusual development of the Fermi surface recently uncovered by
photoemission experiments.Comment: 4 pages, 5 figures, final version appeared in Phys. Rev. Let

### Tension term, interchange symmetry, and the analogy of energy and tension laws of the AdS soliton solution

In this paper, we reconsider the energy and tension laws of the Ricci flat
black hole by taking the contribution of the tension term into account. After
this considering and inspired by the interchange symmetry between the Ricci
flat black hole and the AdS soliton solution which arises from the double
analytic continuation of the time and compact spatial direction, we find out
the analogy of the energy and tension laws of the AdS soliton solution.
Moreover, we also investigate the energy and tension laws of the boosted Ricci
flat black hole, and discuss the boosted AdS soliton solution. However,
although there is the same interchange symmetry between the boosted Ricci flat
black hole and boosted AdS soliton, the analogy of laws of the boosted AdS
soliton solution may be of no sense for the existence of the closed timelike
curves and conical singularity. In spite of that, the conserved charges such as
the energy and momentum of the boosted AdS soliton are well-defined, and an
interesting result is that its energy is lower than that of the static AdS
soliton. On the other hand, note that although the laws obtained above are the
same as those of the asymptotically flat case, the underlying deduced contents
are different. Thus, our results could also be considered as a simple
generalization to the asymptotically AdS case. Moreover, during the
calculation, we find that there may be a new way to define the gravitational
tension which can come from the quasi-local stress tensor of the counter-term
method.Comment: V4: 15 pages, no figure, version to appear in JHE

### A detailed case study of dayside diffuse aurora using GEOTAIL, FAST, and South pole all sky imager

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月26日（月）、27日（火） 国立極地研究所 2階ラウン

### Fully gapped superconductivity in Ni-pnictide superconductors BaNi2As2 and SrNi2P2

We have performed low-temperature specific heat $C$ and thermal conductivity
$\kappa$ measurements on the Ni-pnictide superconductors BaNi$_2$As$_2$
($T_\mathrm{c}$=0.7 K and SrNi$_2$P$_2$ ($T_\mathrm{c}$=1.4 K). The temperature
dependences $C(T)$ and $\kappa(T)$ of the two compounds are similar to the
results of a number of s-wave superconductors. Furthermore, the concave field
responses of the residual $\kappa$ for BaNi$_2$As$_2$ rules out the presence of
nodes on the Fermi surfaces. We postulate that fully gapped superconductivity
could be universal for Ni-pnictide superconductors. Specific heat data on
Ba$_{0.6}$La$_{0.4}$Ni$_2$As$_2$ shows a mild suppression of $T_\mathrm{c}$ and
$H_\mathrm{c2}$ relative to BaNi$_2$As$_2$.Comment: 5 pages, 3 figures, to be published in J. Phys.: Conf. Se

- …