We present a study of thermal conductivity, $\kappa$, in undoped and doped strontium titanate wide temperature range (2-400 K) detecting different regimes heat flow. In SrTiO$_{3}$, $\kappa$ evolves faster than cubic with below its peak narrow window. Such behavior, previously observed handful solids, has been attributed to Poiseuille flow phonons, expected arise when momentum-conserving scattering events outweigh momentum-degrading ones. The effect disappears presence dopants....

We analyze several experimental results, obtained at different pressures, on three heavy-fermion systems using a quantum scaling approach. In spite of the distinct ground states attained by ${\mathrm{CeRu}}_{2}$${\mathrm{Si}}_{2}$, ${\mathrm{UPt}}_{3}$, and ${\mathrm{CeAl}}_{3}$, crossover into dense Kondo regime renormalized Fermi-liquid state these materials in this regime, below coherence line, is shown to exhibit universal behavior. This associated with proximity zero-temperature instability.

We present a study of the transport and magnetic properties series $R\mathrm{NiBC}$ compounds $(R=\mathrm{Er},$ Ho, Dy, Tb, Gd). All materials investigated have long range order at sufficiently low temperatures. Magnetoresistance measurements are presented for large temperatures (T) fields (H). show that below critical temperature, temperature dependence resistivity is determined by electron scattering due to elementary excitations (spin waves) ordered phase values gap in magnon spectra were...

We study the Kondo lattice from point of view scaling theory critical phenomena. The coherence temperature ${\mathrm{scrT}}_{c}$ is associated with a crossover paramagnetic state local moments to Fermi-liquid regime strong magnetic correlations. obtain an expression for in terms Kondo-lattice parameters and exponent ${\ensuremath{\varphi}}_{t}$. effect field investigated characterized by another exponent. These exponents obey relations shifted dimensionality.

The occurrence at low temperatures of an ultrasharp field-induced transition in phase-separated manganites is analyzed. Experimental results show that magnetization and specific-heat steplike transitions below $5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ are correlated with abrupt change the sample temperature, which happens a certain critical field. This temperature rise, magnetocaloric effect, interpreted as produced by released energy point key to understand existence transition. A...

We report macroscopic magnetic measurements carried out in order to detect and characterize field-induced quantum entanglement low-dimensional spin systems. analyze the pyroborate $\mathrm{Mg}\mathrm{Mn}{\mathrm{B}}_{2}{\mathrm{O}}_{5}$ warwickite $\mathrm{Mg}\mathrm{Ti}\mathrm{O}\mathrm{B}{\mathrm{O}}_{3}$, systems with $5∕2$ $1∕2$, respectively. By using susceptibility as an witness we are able quantify a function of temperature field. In addition, experimentally distinguish system...

We present an extensive study of the structural, magnetic, and thermodynamic properties oxyborate ${\text{Co}}_{3}{\text{O}}_{2}{\text{BO}}_{3}$. This is carried out through x-ray diffraction, static dynamic magnetic susceptibilities, specific heat experiments in single crystals a large temperature range. The structure ${\text{Co}}_{3}{\text{O}}_{2}{\text{BO}}_{3}$ composed subunits form three-leg ladders where Co ions with mixed valency are located. this ludwigite determined by competition...

By means of nuclear spin-lattice relaxation rate ${T}_{1}^{\ensuremath{-}1}$, we follow the spin dynamics as a function applied magnetic field in two gapped quasi-one-dimensional quantum antiferromagnets: anisotropic spin-chain system ${\mathrm{NiCl}}_{2}\mathrm{\text{\ensuremath{-}}}4\mathrm{SC}({\mathrm{NH}}_{2}{)}_{2}$ and spin-ladder $({\mathrm{C}}_{5}{\mathrm{H}}_{12}\mathrm{N}{)}_{2}\mathrm{Cu}{\mathrm{Br}}_{4}$. In both systems, excitations are confirmed to evolve from magnons state...

Topological phase transitions can be described by the theory of critical phenomena and identified exponents that define their universality classes. This is a consequence existence diverging length at transition has been as penetration depth surface modes in nontrivial topological phase. In this paper we characterize different classes determining correlation directly from numerical calculations edge function distance to transition. We consider generalizations Su-Schriefer-Heeger (SSH) model,...

There are two known ludwigites containing a single transition metal element, ${\text{Fe}}_{3}{\text{O}}_{2}{\text{BO}}_{3}$ and ${\text{Co}}_{3}{\text{O}}_{2}{\text{BO}}_{3}$. The structure of these materials has low-dimensional units in the form three-legged ladders (3LL) that confer to each them unique magnetic electronic properties. presents staggered charge density wave (CDW) near room temperature transitions. It remained mystery why other compound...

The intermetallic compound ${\mathrm{CeCoGe}}_{2.25}{\mathrm{Si}}_{0.75}$ has an antiferromagnetic transition at ${T}_{N}=5.5 \mathrm{K}.$ Hydrostatic pressure decreases the Neel temperature and drives this system to a quantum critical point (QCP). We characterize approach QCP using electrical resistivity measurements. For $T<{T}_{N}$ is dominated by electron-magnon scattering allows obtain variation of spin-wave gap velocity. find that for significant range close QCP, decrease with while...

We observe for the first time a structural phase transition in oxyborate Fe3O2BO3 which occurs along three leg ladders present this material. X-ray diffraction shows that at 283 K is associated with new where atomic displacements occur alternate directions perpendicular to axis and within plane of ladders. Magnetic data show these lead formation singlet pairs dissociate close transition. Anomalies transport properties also showing related charge ordering phenomenon low dimensional structure.

The oxyborates show a variety of interesting physical behavior associated with the existence low dimensional units in their crystalline structure. In this paper we present transport, x-ray, magnetic, and M\"ossbauer spectroscopy measurements homometallic ludwigites. These results give evidence charge localization reveal an unusual magnetic behavior. We observe reentrant weak ferromagnetism as well coexistence paramagnetic antiferromagnetic spins ${\mathrm{Fe}}_{3}{\mathrm{O}}_{2}{\mathrm{BO}}_{3}.$

We present an extensive study of the structural, magnetic, and thermodynamic properties two heterometallic oxyborates: ${\text{Co}}_{2}{\text{FeO}}_{2}{\text{BO}}_{3}$ ${\text{Ni}}_{2}{\text{FeO}}_{2}{\text{BO}}_{3}$. This has been carried out through x-ray diffraction at room temperature (RT) 150 K, dc ac magnetic susceptibilities, specific-heat experiments in single crystals above 2 K. The these iron ludwigites are discussed comparison with those other known homometallic ludwigites:...

We study the dynamical susceptibility $\ensuremath{\chi}$ of spin glasses above critical temperature using a fractal cluster model. derive scaling relations for zero-field limit real and imaginary parts which are general since they do not depend on particular relaxation Comparison to data ${\mathrm{Eu}}_{0.4}$${\mathrm{Sr}}_{0.6}$S yields exponents in good agreement with independent determinations. discuss different criteria have been used extract time...

We present an extensive study of the oxyborate material ${\text{Co}}_{5}\text{Ti}{({\text{O}}_{2}{\text{BO}}_{3})}_{2}$ using x-ray, magnetic, and thermodynamic measurements. This belongs to a family oxyborates known as ludwigites which presents low-dimensional subunits in form three leg ladders its structure. Differently from previously investigated does not show long-range magnetic order although it goes into spin-glass state at low temperatures. The different techniques employed this...

We report a combined pressure-doping study in the nearly two-dimensional heavy fermion superconductor CeCoIn5 as its superconducting phase is driven to normal state by Sn doping and/or applied pressure. Temperature-pressure-dependent electrical resistivity measurements were performed at vicinity of quantum critical point where Tc→0. A universal plot concentration- and pressure-dependent diagram suggests that for concentrations studied single mechanism responsible reducing Tc bringing system...

The ludwigite ${\text{Co}}_{5}\text{Sn}({\mathrm{O}}_{2}{\text{BO}}_{3}{)}_{2}$ was studied using x-ray diffraction, M\"ossbauer spectroscopy, and magnetic thermodynamic measurements. This material belongs to a family of oxyborates which presents low-dimensional subunits in the form three-leg ladders its structure. confer these materials strong anisotropy their exchange interactions that provide ludwigites several interesting properties, from partial ordering spin-glass states. Despite being...

In this paper, we study the appearance of topological p-wave superconductivity type S=1, Sz=0 in a layer adatoms. This unconventional arises due to an anti-symmetric hybridization between orbitals adatoms and those atoms superconducting BCS substrate. two-dimensional system is topologically non-trivial only absence magnetic field belongs class DIII Altland–Zirnbauer classification. We obtain Pfaffian that characterizes phases its phase diagram. discuss differences case chain with same...

We present an investigation of the magnetic properties ludwigite ${\mathrm{Ni}}_{2}{\mathrm{FeO}}_{2}{\mathrm{BO}}_{3}$. This material is oxyborate that presents in its crystalline structure subunits form walls where transition metal ions are located. Our M\"ossbauer, ac susceptibility, and magnetization measurements show Fe Ni two independent subsystems this down to ${T}_{N}=15$ K. explain behavior terms a hierarchy interactions.