The effect of nonmagnetic impurities on the local density of states in s-wave superconductors

We study the effect of nonmagnetic impurities on the local density of states (LDOS) in s-wave superconductors. The quasiclassical equations of superconductivity are solved selfconsistently to show how LDOS evolves with impurity concentration. The spatially averaged zero-energy LDOS is a linear function of magnetic induction in low fields, N(E=0)=cB/H_{c2}, for all impurity concentration. The constant of proportionality "c" depends weakly on the electron mean free path. We present numerical data for differential conductance and spatial profile of zero-energy LDOS which can help in estimating the mean free path through the LDOS measurement.Comment: 7 pages, 7 figures (high quality color figure available on request

Anisotropic Diamagnetic Response in Type-II Superconductors with Gap and Fermi-Surface Anisotropies

Effects of anisotropic gap structures on a diamagnetic response are investigated in order to demonstrate that the field-angle-resolved magnetization ($M_L(\chi)$) measurement can be used as a spectroscopic method to detect gap structures. Our microscopic calculation based on the quasiclassical Eilenberger formalism reveals that $M_L(\chi)$ in a superconductor with four-fold gap displays a four-fold oscillation reflecting the gap and Fermi surface anisotropies, and the sign of this oscillation changes at a field between $H_{c1}$ and $H_{c2}$. As a prototype of unconventional superconductors, magnetization data for borocarbides are also discussed.Comment: 5 pages, 4 figure

Specific heat and low-lying excitations in the mixed state for a type II superconductor

Low temperature behavior of the electronic specific heat $C(T)$ in the mixed state is by the self-consistent calculation of the Eilenberger theory. In addition to $\gamma T$-term ($\gamma$ is a Sommerfeld coefficient), $C(T)$ has significant contribution of $T^2$-term intrinsic in the vortex state. We identify the origin of the $T^2$-term as (i) V-shape density of states in the vortex state and (ii) Kramer-Pesch effect of vortex core shrinking upon lowering $T$. These results both for full-gap and line node cases reveal that the vortex core is a richer electronic structure beyond the normal core picture.Comment: Accepted in Phys. Rev. B. 5 pages, 5 figure

Electronic state around vortex in a two-band superconductor

Based on the quasiclassical theory, we investigate the vortex state in a two-band superconductor with a small gap on a three dimensional Fermi surface and a large gap on a quasi-two dimensional one, as in MgB_2. The field dependence of zero-energy density of states is compared for fields parallel and perpendicular to the ab plane, and the anisotropy of the vortex core shape is discussed for a parallel field. The Fermi surface geometry of two-bands, combining the effect of the normal-like electronic state on the small gap band at high fields, produces characteristic behavior in the anisotropy of c- and ab-directions.Comment: 6 pages, 6 figures, to appear in Phys. Rev.

Dinamika sadržaja biogenih elemenata u listu i plodu masline sorte Picholine u uvjetima Ulcinjskog polja

In conditions of Ulcinjsko polje, during the period 1987-1991, growth intensity of one-year old olive shoots and fruit growth in Picholine variety were investigated. Related to that, the dynamics of mineral nutrition (N, P, K, Ca and Mg) was followed in leaves and fruits in the period from middle of July to the middle of October. Results showed that nutrient status during vegetation period was within optimal values for olive. Decreasing dynamics during vegetative period was in N (from 2.22% to 1.67%). Slight increasing dynamic was showed in K (1.15% to 1.32%), Ca (0.91% to 1.22%) and Mg (0.17% to 0.21%), while P had a relatively stable content in olive leaves (0.19%). Nutrient status in the fruit showed different tendencies. Decreasing dynamics showed N (0.81 to 0.59%), Ca (260 to 229 ppm) and Mg (228 to 191 ppm). Slight increment showed P (0.13 do 015%) and K (1.44 do 1.51 %).U uvjetima Ulcinjskog polja u razdoblju od 1987. do 1991. istraživani su intezotet rasta jednogodišnjih izdanaka masline I rast ploda sorte Picholine. U vezi s time praćena je dinamika (N,P,K,Ca I Mg) u lišću I plodovima u razdoblju od sredine srpnja do sredine listopada. Rezultati su pokazali da je stanje hraniva u vrijeme vegetacije bilo u rasponu optimalnih vrijednosti za maslinu. Dinamika opadanja u razdoblju vegetacije bila je za N (od 2,22% do 1,33%). Dinamika neznatnog povećanja pokazala se u K (1,15% do 1,32%), Ca (0,91% do 1,33%) I Mg (0,17% do 0,21%) dok je P imao relativno stabilan sadržaj u lišću masline (0,19%). Stanje hraniva u plodu pokazalo je različite tendencije. Dinamiku opadanja pokazali su N (0,82 do 0,59%), Ca (260 do 229 ppm) I Mg (228 do 191 ppm). Lagano povećanje pokazali su P (0,13 do 0,15%) i K (1,44 do 1,51%)

Effect of field dependent core size on reversible magnetization of high-κ\kappa superconductors

The field dependence of the vortex core size $\xi(B)$ is incorporated in the London model, in order to describe reversible magnetization $M(B,T)$ for a number of materials with large Ginzburg-Landau parameter $\kappa$. The dependence $\xi(B)$ is directly related to deviations in $M(\ln B)$ from linear behavior prescribed by the standard London model. A simple method to extract $\xi(B)$ from the magnetization data is proposed. For most materials examined, $\xi(B)$ so obtained decreases with increasing field and is in qualitative agreement both with behavior extracted from $\mu$SR and small angle neutron scattering data and with that predicted theoretically

Genetički aspekti iznenadne smrti kod prirođenih aritmogenih sindroma

Recent research has revealed the genetic etiology of a number of heart diseases that cause sudden cardiac death. Lethal channelopathies are of great importance among the genetically determined heart diseases. Their basic characteristics are unpredictable and deadly nature, autosomal dominant inheritance with variable expressivity and incomplete penetrance in structurally normal heart, and absence of morphological and histological clues that a standard autopsy can identify. Minimum screening of the relatives of sudden cardiac death victims involves taking medical history, physical examination, electrocardiography, echocardiography, and exercise testing. Total positivity of classic genetic tests is only 15%-25%. Even the next generation sequencing technology does not provide a positive result of genetic testing in more than 35% of cases. Therefore, it is necessary to identify a larger number of genes the presence of which can lead to sudden cardiac death, to reduce the number of false positive results, and point to the importance of conducting genetic testing of young victims of sudden cardiac death. Until then, it is enough to preserve 5 g of fresh heart tissue of sudden cardiac death victims at a temperature of -80 °C. The material can be analyzed years later without losing its actuality because it contains information important for the next generation of the sudden cardiac death victim relatives.Novija istraživanja na polju genetike su otkrila nasljednu etiologiju jednog broja srčanih bolesti koje izazivaju iznenadnu srčanu smrt. Smrtonosne kanalopatije su od velike važnosti među genetski uvjetovanim bolestima srca. Njihova temeljna obilježja su nepredvidiva i smrtonosna narav, autosomno dominantno nasljeđe s varijabilnom ekspresivnosti i nepotpunom penetrantnosti u strukturalno normalnom srcu u odsutnosti morfoloških i histoloških naznaka koje se mogu identificirati standardnom obdukcijom. Minimalni odabir srodnika žrtve iznenadne srčane smrti obuhvaća uzimanje anamnestičkih ­podataka, fizikalni pregled, kardiološki pregled, elektrokardiografiju, ehokardiografiju, test opterećenja. Ukupna pozitivnost klasičnih genetskih testova za otkrivanje urođenih bolesti srca je od 15% do 25%. Ni nova generacija tehnologije sekvenciranja ne nudi pozitivan rezultat genetskog testiranja u više od 35% slučajeva, ni uz to što postupak testiranja traje kraće i jeftiniji je. Zato je potrebno identificirati veći broj gena prisustvo kojih može dovesti do iznenadne srčane smrti, smanjiti broj lažno pozitivnih rezultata genetskog testiranja, sigurnije ukazati na značenje provođenja genetskog testiranja mladih žrtava iznenadne srčane smrti, kako bi genetsko testiranje postalo dio standardnog dijagnostičkog postupka. Do tada je dovoljno uzeti i sačuvati 5 g svježeg srčanog tkiva žrtve iznenadne srčane smrti na temperaturi od -80 ˚C. Uzeti materijal može se analizirati i mnogo godina nakon uzimanja ne gubeći na aktualnosti, jer u sebi sadrži informaciju od važnosti za sljedeće generacije srodnika žrtve iznenadne srčane smrti

Reentrant vortex lattice transformation in four-fold symmetric superconductors

The physics behind the rhombic$\to$square$\to$rhombic flux line lattice transformation in increasing fields is clarified on the basis of Eilenberger theory. We demonstrate that this reentrance observed in LuNi$_2$B$_2$C is due to intrinsic competition between superconducting gap and Fermi surface anisotropies. The calculations reproduce not only it but also predict yet not found lock-in transition to a square lattice with different orientation in higher field. In view of physical origin given, this sequence of transitions is rather generic to occur in four-fold symmetric superconductors.Comment: 5 pages, 4 figures,submitted to Phys. Rev. Let

Quasi-Classical Calculation of the Mixed-State Thermal Conductivity in s-Wave and d-Wave Superconductors

To see how superconducting gap structures affect the longitudinal component of mixed-state thermal conductivity kappa_{xx}(B), the magnetic-field dependences of kappa_{xx}(B) in s-wave and d-wave superconductors are investigated. Calculations are performed on the basis of the quasi-classical theory of superconductivity by fully taking account of the spatial variation of the normal Green's function, neglected in previous works, by the Brandt-Pesch-Tewordt approximation. On the basis of our result, we discuss the possibility of kappa_{xx}(B) measurement as a method of probing the gap structure.Comment: To appear in J. Phys. Soc. Jp