박투선 교수

The low-frequency dielectric response of hole-doped insulators La(2)Cu(1-x)Li(x)O(4) and La(2-x)Sr(x)NiO(4) shows a large dielectric constant epsilon(') at high temperature and a steplike drop by a factor of 100 at a material-dependent low temperature T(f). T(f) increases with frequency, and the dielectric response shows universal scaling in a Cole-Cole plot, suggesting that a charge-glass state is realized both in the cuprates and in the nickelates.

Field-angle dependent heat capacity of the nonmagnetic borocarbide superconductor YNi2B2C reveals a clear fourfold oscillation, the first observation of its kind. The observed angular variations were analyzed as a function of magnetic field angle, field-intensity, and temperature to provide its origin. The quantitative agreement between experiment and theory strongly suggests that we are directly observing nodal quasiparticles generated along <100> by the Doppler effect. The results demonstrate

Superconductivity develops from an attractive interaction between itinerant electrons that creates electron pairs, which condense into a macroscopic quantum state-the superconducting state. On the other hand, magnetic order in a metal arises from electrons localized close to the ionic core and whose interaction is mediated by itinerant electrons. The dichotomy between local moment magnetic order and superconductivity raises the question of whether these two states can coexist and involve the sam

When antiferromagnetism and unconventional superconductivity coexist in CeRhIn(5) there is a significant temperature difference between resistively and thermodynamically determined transitions into the superconducting state. In this state, anisotropic transport near the superconducting transition reveals the emergence of textured superconducting planes that appear without a change in translational symmetry of the lattice. CeRhIn(5) is not unique in exhibiting these behaviors, indicating that tex

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We report field-orientation specific heat studies of the pressure-induced heavy-fermion superconductor CeRhIn5. These experiments provide the momentum-dependent superconducting gap function for the first time in any pressure-induced superconductor. In the coexisting phase of superconductivity and antiferromagnetism, field rotation within the Ce-In plane reveals fourfold modulation in the density of states, which favors a d-wave order parameter and constrains a theory of the interplay between sup

A study of the dependence of the heat capacity C(p)(alpha) on the field angle in LuNi2B2C reveals an anomalous disorder effect. For pure samples, C(p)(alpha) exhibits a fourfold variation as the field H<H(c2) is rotated in the [001] plane, with minima along <100> (alpha=0). A slightly disordered sample, however, develops anomalous secondary minima along <110> for mu(0)H>1 T, leading to an eightfold pattern at 2 K and 1.5 T. The anomalous pattern is discussed in terms of coexisting superconductin

The complex magnetic transitions and superconductivity of ${\mathrm{HoNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ were studied via the dependence of the heat capacity on temperature and in-plane field angle. We provide an extended, comprehensive magnetic phase diagram for $B\ensuremath{\Vert}[100]$ and $B\ensuremath{\Vert}[110]$ based on the thermodynamic measurements. Three magnetic transitions and the superconducting transition were clearly observed. The 5.2 K transition ${(T}_{N})$ shows a hysteresis

We report a study on tuning the charge density wave (CDW) ferromagnet SmNiC2 to a weakly coupled superconductor by substituting La for Sm. X-ray diffraction measurements show that the doped compounds obey Vegard's law, where La (Lu) alloying expands (shrinks) the lattice due to its larger (smaller) atomic size than Sm. In the series Sm1-xLaxNiC2, CDW transition (TCDW = 148 K) for SmNiC2 is gradually suppressed, while the ferromagnetic (FM) ordering temperature (TC) at 17 K slightly increases up

The specific heat of polycrystalline ${\mathrm{Mg}}^{11}{\mathrm{B}}_{2}$ has been measured with high-resolution ac calorimetry from 5 to 45 K at constant magnetic fields. The excess specific heat above ${T}_{c}$ is discussed in terms of Gaussian fluctuations and suggests that ${\mathrm{Mg}}^{11}{\mathrm{B}}_{2}$ is a bulk superconductor with Ginzburg-Landau coherence length ${\ensuremath{\xi}}_{0}=26\mathrm{\AA{}}.$ The transition-width broadening in field is treated in terms of lowest-Landau-l

The mixed-valence compound was investigated by electrical resistivity and ac specific heat at low temperatures and high pressures. At atmospheric pressure, its Kadowaki-Woods (KW) ratio A/gamma2 is 16 times smaller than the universal value RKW(=1.0x10(-5) microOmega.cm.mol2.K2.mJ-2), but sharply increases to 16.5RKW at 27 kbar. The pressure-induced change in the KW ratio and deviation from RKW are analyzed in terms of the change in f-orbital degeneracy N and carrier density n. This analysis is f

Abstract When subjected to pressure, the prototypical heavy‐fermion antiferromagnet CeRhIn 5 becomes superconducting, forming a broad dome of superconductivity (SC) centred around 2.35 GPa (= P 2) with maximal T c of 2.3 K. Above the superconducting dome, the normal state shows strange metallic behaviours, including a divergence in the specific heat and a sub‐ T ‐linear electrical resistivity. The discovery of a field‐induced magnetic phase that coexists with SC for a range of pressures P ≤ P 2

We report the fabrication and physical characteristics of niobium ion (Nb⁵⁺)-doped double-crossover DNA (DX-DNA) and salmon DNA (SDNA) thin films. Different concentrations of Nb⁵⁺ ([Nb⁵⁺]) are coordinated into the DNA molecules, and the thin films are fabricated via substrate-assisted growth (DX-DNA) and drop-casting (SDNA) on oxygen plasma treated substrates. We conducted atomic force microscopy to estimate the optimum concentration of Nb⁵⁺ ([Nb<sup>5