Determining the types of superconducting order in quantum materials is a challenge, especially when multiple degrees of freedom, such as bands or orbitals, contribute to the fermiology and when superconductivity competes, intertwines, or coexists with other symmetry-breaking orders. Here, we study the Kagome-lattice superconductor CsV3Sb5, in which multiband superconductivity coexists with a charge order that substantially reduces the compound's space group symmetries. Through a combination of thermodynamic as well as electrical and thermal transport measurements, we uncover two superconducting regimes with distinct transport and thermodynamic characteristics, while finding no evidence for a phase transition separating them. Thermodynamic measurements reveal substantial quasiparticle weight in a high-temperature regime. At lower temperatures, this weight is removed via the formation of a second gap. The two regimes are sharply distinguished by a pronounced enhancement of the upper critical field at low temperatures and by a switch in the anisotropy of the longitudinal thermal conductivity as a function of in-plane magnetic field orientation. We argue that the band with a gap opening at lower temperatures continues to host low-energy quasiparticles, possibly due to a nodal structure of the gap. Taken together, our results present evidence for band-selective superconductivity with remarkable decoupling of the (two) superconducting gaps. The commonly employed multiband scenario, whereby superconductivity emerges in a primary band and is then induced in other bands appears to fail in this unconventional kagome superconductor. Instead, band-selective superconducting pairing is a paradigm that seems to unify seemingly contradicting results in this intensely studied family of materials and beyond.

Giant magnetoresistance (GMR) in bulk nonmagnetic compounds has received considerable attention since this phenomenon challenged the classical understanding of electron transport under a magnetic field. Here, we report magnetotransport properties of the diamagnetic intermetallic compound YCd6 for applied magnetic fields up to 35 T and temperatures down to 0.4 K that reveal GMR. We argue that the large MR value can be explained in terms of field-induced pseudogaps on a Fermi surface. These results are relevant to the understanding of the Fermi-surface topology of quasicrystal approximants.

The anomalous Hall, Nernst and thermal Hall coefficients of Fe$_{3-x}$GeTe$_2$ display several features upon cooling, like a reversal in the Nernst signal below $T = 50$ K pointing to a topological transition (TT) associated to the development of magnetic spin textures. Since the anomalous transport variables are related to the Berry curvature, a possible TT might imply deviations from the Wiedemann-Franz (WF) law. However, the anomalous Hall and thermal Hall coefficients of Fe$_{3-x}$GeTe$_2$ are found, within our experimental accuracy, to satisfy the WF law for magnetic-fields $\mu_0H$ applied along its inter-layer direction. Surprisingly, large anomalous transport coefficients are also observed for $\mu_0H$ applied along the planar \emph{a}-axis as well as along the gradient of the chemical potential, a configuration that should not lead to their observation due to the absence of Lorentz force. However, as $\mu_0H$ $\|$ \emph{a}-axis is increased, magnetization and neutron scattering indicate just the progressive canting of the magnetic moments towards the planes followed by their saturation. These anomalous planar quantities are found to not scale with the component of the planar magnetization ($M_{\|}$), showing instead a sharp decrease beyond $\sim \mu_0 H_{\|} = $ 4 T which is the field required to align the magnetic moments along $\mu_0 H_{\|}$. We argue that locally chiral spin structures, such as skyrmions, and possibly skyrmion tubes, lead to a field dependent spin-chirality and hence to a novel type of topological anomalous transport. Locally chiral spin-structures are captured by our Monte-Carlo simulations incorporating small Dzyaloshinskii-Moriya and biquadratic exchange interactions.

In the present work, the dynamics of the spins and the structural parameters of thermal treated samples of Eu1−xFexCrO3 (x = 0, 0.1 and 0.2) were investigated. The ac-magnetic susceptibility (χac) was measured near TN for frequencies (f) in the range 10 - 104 Hz, magnitude of the ac magnetic field of 10 Oe and for 5 ≤ T ≤ 300 K. X-ray diffraction data were used for determining the lattice parameters and the bonding angle θB (Cr– O(2) – Cr) for 100 ≤ T ≤ 300 K. The maximum in χac was found to shift to higher values of T for increasing values of f. The Vogel-Fulcher law was used for analyzing χac yielding values for the characteristic relaxation time τ0, activation energy Ea/kB and glassy temperature TG, respectively, in the ranges 2.10 - 3.96 ps, 46.5 - 47.2 K and 169.9 -176.1 K. The super-exchange parameter J∼cos4180−θB/2/d7, where d is the length of the bound Cr-O(2), was also obtained yielding a good correlation with the corresponding values of TN.

Amorphous FexZr100−x alloys display a complex magnetic phase diagram, particularly in the range 89% ≲ x ≲ 93% in which the phase transition from the paramagnetic to a soft ferromagnetic (FM) state at a critical temperature Tc precedes a second transition at Txy < Tc to a transverse spin-glass (SG) phase, with frozen spin components transverse to the magnetization. The softness of the FM phase and the coexistence of FM and SG orderings complicate exploring the low-temperature and low-field critical properties of the glassy transition. Here we study the irreversibility Almeida-Thouless (AT) line that marks the onset of the transverse SG phase in the Fe90Zr10 alloy in the low-field regime up to H = 60 Oe. While ZFC measurements give rise to an AT exponent ϕ = 4.6, similar to that of another amorphous FM compound with random local anisotropy, the induction of magnetic shiftings upon cooling the sample in a large field, − 85 kOe, displaces down the AT line and separates it into two distinct regimes: one also with ϕ = 4.6 for H above 20 Oe, nearly corresponding to the typical field to flip the remanent magnetization, and a new second regime at lower H, with field-induced remanent clusters and exponent ϕ = 3.6 that approaches the mean-field value ϕ = 3. Our findings are discussed on the light of the results from a random nonuniform anisotropy model with FM exchange interactions, which also reported the existence of a two-regimes scenario in the AT line with similar exponents.

The ferrimagnetic insulator yttrium iron garnet (YIG) is one of the most important materials in the active fields of insulator-based spintronics and spin caloritronics. Nevertheless, and despite the fact that this material has been studied for over six decades, the thermal properties of magnons in YIG have not been sufficiently characterized, mainly because at not very low temperatures they are overwhelmed by the contribution of phonons. Here, we report measurements of the thermal conductivity in YIG under magnetic fields up to 31.4 T to increase the magnon energy gap, to suppress the magnon contribution, and to isolate that of the phonons relative to their behavior at zero field. We observe that at a temperature of 20 K, even with a field as large as 31.4 T, the magnon contribution is not completely suppressed. The magnon thermal conductivity, measured by subtracting the value of the total thermal conductivity at 31.4 T from the value at zero field, has a peak at 16 K, with an amplitude that is over five times larger than the one obtained by measuring under a field of only 7 T, as previously reported.

Phosphate ions perform a variety of functions in metabolic processes and are essential for all living organisms. The determination of the concentration of phosphate ions is useful in clinical diagnosis of various diseases as an inadequate phosphate level could lead to many health problems. In the search for a cost-effective method of fast monitoring, we investigated the use of cobalt ferrite nanoparticles (CoFeNPs) in the selective recognition of phosphate ions dissolved in aqueous media and more complex samples, such as human blood serum. We prepared these NPs by a chemical coprecipitation route and subjected them to annealing at 600 °C for 1 h. The successful formation of the NPs was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and hysteresis loop measurements. The NPs exhibited a ferrimagnetic behavior, a spinel-type crystalline structure, and hexagonal shape in the nanoscale range. We demonstrated that CoFeNPs containing immobilized fluorescent-labeled single-chain DNA (ssDNA*) probes can be applied for the fast selective detection of phosphate ions dissolved in a liquid medium. We have explored the fact that phosphate groups can displace ssDNA* probes attached to the nanoparticles, therefore causing a perceptible change in the fluorescence signal of the supernatant liquid. This detection method has been tested for the sensing of phosphate ions present both in aqueous solutions and in biological samples, with excellent selectivity and a low limit of detection (∼1.75 nM).

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In this work, we have synthesized six coordination polymers [Ln2(Thz)3·8H2O)]·4H2O (Ln = La3+, Ce3+, Nd3+, Sm3+, Eu3+, Gd3+; Thz = thiazolo[5,4-d]thiazole-2,5-dicarboxylate). These are the first structures combining this ligand with lanthanides. All compounds crystallize in the P-1 triclinic system, forming a 2-D coordination network. Luminescence spectra for the Nd3+, Sm3+, and Eu3+ structures show the typical transitions of these ions, through the antenna effect promoted by the ligand. The magnetic properties of Ce3+, Nd3+, Sm3+, Eu3+, Gd3+ compounds were analyzed in terms of the free ion approximation. The variable-temperature susceptibility fitted with a Curie-Weiss law shows the existence of weak magnetic interactions at low temperatures for the Ce3+, Nd3+ and Sm3+ compounds, and paramagnetic behavior for the Gd3+ compound.

The magnetic properties of nanoparticles of Eu1-xFexCrO3 (0 < x < 1) prepared by a combustion reaction technique were investigated. An irreversible behavior in the magnetization was observed for a sample with x = 0.10 below the Neel temperature (T-N) yielding a complex phase diagram. The irreversibility data was fitted to a de Almeida-Thouless line by using phi = 3.0 for the critical exponent and a glassy temperature T-G of 174.4 K for H <= 40 kOe. The dynamics of the spins was investigated by measuring the ac magnetic susceptibility (chi(ac)) near T-N for frequencies (f) in the range 10-10(4) Hz. The maximum in cac was found to shift to higher values of T for increasing values of f, yielding =0.003 for the shift per decade of f parameter. The Voguel-Fulcher law and a power-law were used for analyzing chi(ac) yielding t(0) = 1: 8 x 10(-9) s (= 1.6 x 10(-15) s) for the characteristic relaxation time, E-a/k(B) = 39.23 K for the activation energy and T-G= 165.9 K (= 167.5 K) for the Voguel-Fulcher (power-law) model. Moreover, the power-law yielded zv - 5.62 for the product of the dynamical critical exponent (v) with the one associated to the correlation length (z). The dependence of T-N with the bonding angles Cr-3 (broken vertical bar)-O-2-Cr-3 (broken vertical bar) was investigated for as-prepared samples yielding a trend contrary to the expected. The overall results were accounted for by taking into consideration the microstrain introduced by the sample preparation technique and by the ionic dopping. (C) 2017 Elsevier B.V. All rights reserved.

Multiferroic ceramics of Bi0.99Y0.01Fe1-xNixO3 with 0.01 <= x <= 0.05 were synthesized by using a modified solid state reaction method. The crystalline structure and the morphology of the samples were investigated by X-ray diffraction (XRD) and by scanning electron microscopy (SEM). The addition of Y and Ni to the bismuth ferrite (BiFeO3) was found to decrease the average grain size. Ac magnetic susceptibility and the zero-field-cooled (ZFC) and field-cooled (FC) magnetizations were measured for temperatures in the range 5 <= T <= 300 K. Hysteresis loops and an irreversible behavior in the temperature dependence of the magnetization not present in pure BiFeO3 were observed in the doped samples. However, the ferromagnetism was found more likely to be due to the presence of small amounts of magnetite. Nevertheless, the determination of the amount of Fe3O4 in these composite materials is important because it influences the magnetoelectric coupling which is important for some technological applications. (C) 2017 Elsevier B. V. All rights reserved.