8,735 research outputs found
Doping dependence of the upper critical field in La_{2-x}Sr_xCuO_4 from specific heat
The low-temperature specific heat of La_{2-x}Sr_xCuO_4 (LSCO) single crystals
in magnetic field H up to 12 T has been examined over a wide range of doping
(0.063=< p =<0.238). From this we have mapped the upper critical field H_{c2}
of LSCO across the entire superconducting diagram. It is found that the H_{c2}
shows a doping dependence similar to that of the critical temperature T_c. We
have discussed the implications of the result and proposed that there may be an
effective superconducting energy scale responsible for the H_{c2} behavior in
the underdoped region.Comment: 6 pages,3 figures,1 tabl
Smooth densities of the laws of perturbed diffusion processes
Under some regularity conditions on , and , we prove that
the following perturbed stochastic differential equation \begin{equation}
X_t=x+\int_0^t b(X_s)ds+\int_0^t \sigma(X_s) dB_s+\alpha \sup_{0 \le s \le t}
X_s, \ \ \ \alpha<1 \end{equation} admits smooth densities for all , where is some finite number
Gravitational waves with dark matter minispikes: the combined effect
It was shown that the dark matter(DM) minihalo around an intermediate mass
black hole(IMBH) can be redistributed into a cusp, called the DM minispike. We
consider an intermediate-mass-ratio inspiral consisting of an IMBH harbored in
a DM minispike with nonannihilating DM particles and a small black hole(BH)
orbiting around it. We investigate gravitational waves(GWs) produced by this
system and analyze the waveforms with the comprehensive consideration of
gravitational pull, dynamical friction and accretion of the minispike and
calculate the time difference and phase difference caused by it. We find that
for a certain range of frequency, the inspiralling time of the system is
dramatically reduced for smaller central IMBH and large density of DM. For the
central IMBH with , the time of merger is ahead, which can be
distinguished by LISA, Taiji and Tianqin. We focus on the effect of accretion
and compare it with that of gravitational pull and friction. We find that the
accretion mass is a small quantity compared to the initial mass of the small BH
and the accretion effect is inconspicuous compared with friction. However, the
accumulated phase shift caused by accretion is large enough to be detected by
LISA, Taiji and Tianqin, which indicate that the accretion effect can not be
ignored in the detection of GWs.Comment: 10 pages, 14 figure
- …