Abstract:
When we first started introducing guest posts, Char Booth was a name mentioned by many of us at ItLwtLP. As a blogger over at info-mational, Char has introduced ideas that are uniquely critical and thoughtful. (A good example would be Char’s guest post at Tame the Web about The Library Student Bill of Rights.) You [...]

Abstract:
We calculate the superconducting critical temperature $T_c$, the singlet pair function $\Psi^+(x)$, and triplet pair function $\Psi^-(x)$ of superconductor/normal metal/ferromagnet (S/N/F) trilayers using the linearized Usadel equation near $T_c$. The Green's function method developed by Fominov $et al.$ for the S/F bilayers is extended to the S/N/F trilayer systems. The S of the trilayers is taken to be an s-wave singlet pairing superconductor, and the S/N and N/F interfaces are modeled in terms of the interface resistances parameterized, respectively, by $\gamma_b^{SN}$ and $\gamma_b^{NF}$. We present the $T_c$, $\Psi^+(x)$, and $\Psi^-(x)$ for typical $\gamma_b^{SN}$, $\gamma_b^{NF}$, and the exchange energy $ E_{ex}$: (a) For a small (large) $\gamma_b^{NF}$, $T_c$ of S/N/F trilayers, as $d_N$ is increased, increases (decreases) on the length scale of N coherence length $\xi_N$ with a discontinuity at $d_N=0$ due to a boundary condition mismatch. (b) $T_c(d_F)$ shows a non-monotonic behavior like S/F bilayers with a weakened shallow dip. (c) The odd frequency triplet component $\Psi^-(x)$, induced by $E_{ex}$ and proximity effects, has a maximum near the N/F interface and decreases on the length scale $\xi_{ex}$ in F. It also penetrates into N and S regions on the length scale $\xi_N$ and $\xi_S$, respectively. Based on these results we make comments on the experimental observation of the odd triplet components and the recent $T_c$ measurements in Nb/Au/CoFe trilayer systems.

Abstract:
We have experimentally investigated the density of states (DOS) in Nb/Ni (S/F) bilayers as a function of Ni thickness, $d_F$. Our thinnest samples show the usual DOS peak at $\pm\Delta_0$, whereas intermediate-thickness samples have an anomalous ``double-peak'' structure. For thicker samples ($d_F \geq 3.5$ nm), we see an ``inverted'' DOS which has previously only been reported in superconductor/weak-ferromagnet structures. We analyze the data using the self-consistent non-linear Usadel equation and find that we are able to quantitatively fit the features at $\pm\Delta_0$ if we include a large amount of spin-orbit scattering in the model. Interestingly, we are unable to reproduce the sub-gap structure through the addition of any parameter(s). Therefore, the observed anomalous sub-gap structure represents new physics beyond that contained in the present Usadel theory.

Abstract:
We have investigated the superconducting critical temperatures of Nb/Au/CoFe trilayers as a function of Au and CoFe thicknesses. Without the CoFe layer the superconducting critical temperatures of Nb/Au bilayers as a function of Au thickness follow the well-known proximity effect between a superconductor and a normal metal. The superconducting critical temperatures of Nb/Au/CoFe trilayers as a function of Au thickness exhibit a rapid initial increase in the small Au thickness region and increase slowly to a limiting value above this region, accompanied by a small oscillation of Tc. On the other hand, the superconducting critical temperatures of Nb/Au/CoFe trilayers as a function of CoFe thickness show non-monotonic behavior with a shallow dip feature. We analyzed the Tc behavior in terms of Usadel formalism and found that most features are consistent with the theory, although the small oscillation of Tc as a function of the Au thickness cannot be accounted for. We have also found quantitative values for the two interfaces: Nb/Au and Au/CoFe.

Abstract:
We have studied the behavior of the superconducting critical temperature Tc in $Nb/Co_{60}Fe_{40}$, Nb/Ni, and $Nb/Cu_{40}Ni_{60}$ bilayers as a function of the thickness of each ferromagnetic metal layer. The Tc s of three sets of bilayers exhibit non-monotonic behavior as a function of each ferromagnetic metal thickness. Employing the quantitative analysis based on Usadel formalism of the effect of the exchange energy, we observed that the Tc behavior of $Nb/Co_{60}Fe_{40}$ bilayers is in good agreement with the theoretical values over the entire range of the data. On the other hand, the Tc s of Nb/Ni and $Nb/Cu_{40}Ni_{60}$ bilayers show a higher value in the small thickness regime than the theoretical prediction obtained from the calculation, which matches the dip position and the saturation value of Tc in the large thickness limit. This discrepancy is probably due to the weakened magnetic properties of Ni and $Cu_{40}Ni_{60}$ when they are thin. We discuss the values of our fitting parameters and its implication on the validity of the current Usadel formalism of the effect of the exchange energy.

Abstract:
The measurement of $1.97 \pm 0.04 M_{solar}$ for PSR J1614-2230 and $2.01 \pm 0.04M_{solar}$ for PSR J0348+0432 puts a strong constraint on the neutron star equation of state and its exotic composition at higher densities. In this paper, we investigate the possibility of exotic equation of state within the observational mass constraint of $2M_{solar}$ in the framework of relativistic mean field model with density-dependent couplings. We particularly study the effect of antikaon condensates in the presence of hyperons on the mass-radius relationship of the neutron star.

Abstract:
In the following pages I will try to give a solution to this very known unsolved problem of theory of numbers. The solution is given here with an important analysis of the proof of formula (4.18), with the introduction of special intervals between square of prime numbers that I call silver intervals _{}. And I make introduction of another also new mathematic phenomenon of logical proposition “In mathematics nothing happens without reason” for which I use the ancient Greek term “catholic information”. From the theorem of prime numbers we know that the expected multitude of prime numbers in an interval _{} is given by formula _{？}considering that interval as a continuous distribution of real numbers that represents an elementary natural numbers interval. From that we find that in the elementary interval _{} around of a natural number ν we easily get by dx=1 the probability _{} that has the ν to be a prime number. From the last formula one can see that the second part _{} of formula (4.18) is absolutely in agreement with the above theorem of prime numbers. But the benefit of the (4.18) is that this formula enables correct calculations in set N on finding the multitude of twin prime numbers, in contrary of the above logarithmic relation which is an approximation and must tend to be correct as ν tends to infinity. Using the relationship (4.18) we calculate here the multitude of twins in N, concluding that this multitude tends to infinite. But for the validity of the computation, the distribution of the primes in a random silver interval _{} is examined, proving on the basis of catholic information that the density of primes in the same random silver interval _{} is statistically constant. Below, in introduction, we will define this concept of “catholic information” stems of “information theory” [1] and it is defined to use only general forms in set N, because these represent the set

Abstract:
We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its band gap is large. The Hall mobility of Ba0.98La0.02SnO3 crystals with the n-type carrier concentration of \sim 8-10\times10 19 cm-3 is found to be \sim 103 cm2 V-1s-1 at room temperature, and the precise measurement of the band gap \Delta of a BaSnO3 crystal shows \Delta=4.05 eV, which is significantly larger than those of other transparent conductive oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO3 is a promising candidate for transparent conductor applications and also epitaxial all-perovskite multilayer devices.