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Superconductivity in infinite-layer nickelates holds exciting analogies with that of cuprates, with similar structures and 3d-electron count. Using resonant inelastic x-ray scattering, we studied electronic and magnetic excitations and charge density correlations in Nd_{1-x}Sr_{x}NiO_{2} thin films with and without an SrTiO_{3} capping layer. We observe dispersing magnons only in the capped samples, progressively dampened at higher doping. We detect an elastic resonant scattering peak in the uncapped x=0 compound at wave vector (∼⅓,0), remindful of the charge order signal in hole doped cuprates. The peak weakens at x=0.05 and disappears in the superconducting x=0.20 film. The role of the capping on the electronic reconstruction far from the interface remains to be understood.

Restoring strangeness Cuprate superconductors host a number of complex phases, and elucidating their relationship to each other may shed light on the nature of cuprate superconductivity. Two of these intriguing phases are the strange metal phase and the charge-density wave (CDW) order, which appear next to each other in the cuprate phase diagram. The hallmark of the strange metal phase, the linear dependence of electrical resistivity on temperature, disappears in the CDW phase. Wahlberg et al . strained thin films of the cuprate YBa 2 Cu 3 O 7–δ to suppress CDW order (see the Perspective by Le Tacon). Using resonant inelastic x-ray scattering and transport measurements, the researchers found that suppressing CDW restored the linear-in-temperature resistivity in the CDW portion of the phase diagram. —JS

The transport properties of a YBa2Cu3 O 7 - δ superconducting quantum interference device (SQUID) based on grooved Dayem bridge weak links are studied as a function of temperature: at high temperatures (60 K < T < T c = 89 K), the weak links show properties similar to superconductor-normal conductor-superconductor junctions, while at temperatures below 60 K, the weak links behave like short Dayem bridges. Using these devices, we have fabricated SQUID magnetometers with galvanically coupled in-plane pickup loops: at T = 77 K, magnetic field white noise levels as low as 63 fT/ Hz have been achieved.

We have studied the low temperature electrical transport properties of La

Charge density modulations have been observed in all families of high-critical temperature (

Nanowires of Y-Ba-Cu-O, with the thickness of 50 nm and the width ranging from 90 nm to 500 nm have been successfully grown on lanthanum aluminate substrates for photon detection experiments. The nanowires were up to 10-mu m long and formed a meander structure, covering the area of up to 30x10 mu m(2) with a fill factor of 50%. The samples were excited using optical laser pulses at a 1550 nm wavelength and resulting photoresponse signals were measured as a function of both temperature and normalized bias current. Presence of two, distinct regimes in the photoresponse temperature dependence has been clearly evidenced, suggesting different physical mechanisms of the signal formation. Presented experimental results shed new light on prospects of implementation of high-temperature superconducting oxides in photon detection and counting.

We present femtosecond pump-probe spectroscopy studies of time-resolved optical reflectivity of all-oxide YBa2Cu3O7/La0.7Sr0.3MnO3 (YBCO/LSMO) superconductor/ferromagnet (S/F) bilayers consisting of a 100-nm-thick YBCO base layer and either 10 or 35 nm LSMO cap thickness. At temperatures far below the YBCO superconducting transition T-C, samples with a 10 nm F overlayer show a photoresponse that is similar to, but faster than, pure-YBCO, 100-nm-thick reference samples, while close to T-C and above (up to similar to 160 K) we observe a signature of both the electronic and spin response that cannot be interpreted as an incoherent sum of contributions from the two layers. The photoresponse of the S/F structures with the 35-nm LSMO layer always qualitatively follows that of the pure LSMO, but with a shorter relaxation time. In all cases, the YBCO/LSMO nonequilibrium dynamics can be modeled using a generalized multitemperature model, which is a superposition of the dynamics of the three-temperature models that are used to describe the superconductor and ferromagnet subsystems, respectively. The long term of the photoresponse signal of the S/F bilayer can be well fitted with the two characteristic relaxation times. DOI: 10.1103/PhysRevB.87.134514

We have investigated the zero-field critical supercurrent of YBa(2)Cu(3)O(7-δ) bridges patterned from 50 nm thick films as a function of bridge width, ranging from 2 μm to 50 nm. The critical current density monotonically increases for decreasing bridge width even for widths smaller than the Pearl length. This behavior is accounted for by considering current crowding effects at the junction between the bridge and the wider electrodes. Comparison to numerical calculations of the current distributions in our bridge geometries of various widths yields a (local) critical current density at 4.2 K of 1.3×10(8) A/cm(2), the Ginzburg Landau depairing current density. The observation of up to 160 Shapiro-like steps in the current voltage characteristics under microwave irradiation substantiates the pristine character of our nanobridges with cross sections as small as 50×50 nm(2).

Cutaneous focal blood perfusion and an index of cutaneous vascular resistance were determined on the dorsum and palm of the hand of 34 patients with liver cirrhosis and of 24 healthy control subjects. Tests were performed with a laser-Doppler technique before and during stimulation of the vasoconstrictor venoarterial reflex, performed by means of venous occlusion of the forearm. The mean arterial blood pressure of the cirrhotics turned out to be lower than that of the controls. On the dorsum of their hands a normal blood perfusion and a reduced vascular resistance were verified, suggesting the intervention of a local autoregulatory phenomenon of the blood flow. The blood perfusion turned out to be higher, whereas the vascular resistance was lower than the norm on the palm of the hands of cirrhotic patients who had palmar erythema, showing the presence of an anomalous non-autoregulatory vasodilation. The extent of venoarterial reflex on the dorsum of the hand turned out to be identical in the patients and controls, whereas that on the palm turned out depressed. This anomaly was present also in patients without palmar erythema, although less marked than in those with erythema. The data obtained suggest the presence of a disturbance in the functioning of the arteriovenous anastomoses (numerous in the palm but very scarce in the dorsum), superimposed on the venoarterial reflex. It may depend on the existence, in hepatic cirrhosis, of an impairment of the specialized autonomic nervous mechanisms that control temperature loss.

The effects were studied of the total triterpenic fraction of Centella asiatica on serum levels of the uronic acids and lysosomal enzymes involved in mucopolysaccharide metabolism (beta-glycuronidase, beta-N-acetylglucosaminidase, arylsulfatase) in patients with varicose veins. The basal levels of uronic acids (467.7 +/- 69.3 micrograms/ml) and of lysosomal enzymes (beta-glycuronidase 1.8 +/- 0.4 microM/min/l, beta-N-acetylglucosaminidase 23.1 +/- 0.4 microM/min/l, arysulfatase 0.078 +/- 0.003 microM/min/l) were elevated, indicating an increased mucopolysaccharide turnover in subjects with varicose veins. During treatment with Centella asiatica extract (60 mg/day for three months), these levels fell progressively. At the end of treatment the serum uronic acid (231.8 +/- 51.5 micrograms/ml), beta-glycuronidase (1.2 +/- 0.05 microM/min/l), beta-N-acetylglucosaminidase (17.7 +/- 0.7 microM/min/l) and arysulfatase (0.042 +/- 0.003 microM/min/l) levels were highly significantly lower than the basal levels (p less than 0.01). The results of this trial provide an indirect confirmation of regulatory effects of the extract of Centella asiatica on metabolism in the connective tissue of the vascular wall.

The cutaneous postischemic hyperemia test, by means of laser Doppler flowmetry, was carried out on 71 normal, healthy lower extremities and 138 lower limbs suffering from peripheral occlusive arterial disease. The test, a new technique for evaluating the hemodynamics of limbs, permitted a clear distinction between normal, healthy subjects and patients suffering from arterial disorders. It was also seen that the degree of deterioration in the quantitative parameters was quite obviously related to the seriousness of the clinical picture. A comparison of the more severely and less severely affected limbs of each patient and the values taken bilaterally gave a correspondence of 98.6%. A therapeutic cycle consisting of the intraarterial administration of naftidrofuryl in 20 limbs achieved a statistically significant improvement in two parameters (tL and tR). Four limbs were treated with percutaneous transluminal angioplasty. After treatment the values obtained with the test were found to be absolutely normal. It is therefore suggested that this test be widely adopted in vascular diagnostic laboratories.

A method for evaluating reactive postischemic hyperemia on the skin using the laser Doppler velocimeter is described. The study was conducted on healthy subjects and on patients affected by chronic occlusive arterial disease of the lower limbs at the second clinical stage. The laser Doppler probe is applied to the pulp of the hallux and the inflatable cuff is used for the transient occlusion of arteries both around the thigh and around the ankle. The data obtained are significant for differences between patients and controls and suggest that the cutaneous postischemic hyperemia test is of diagnostic value. The test may be used both for screening and in the follow-up of the peripheral occlusive arterial disease.

The effects provoked in different points of skin circulation by a vasoactive drug injected in the femoral artery of patients affected by chronic obliterative arterial disease at clinical stage 2, were evaluated using the laser Doppler velocimeter. At the same time, by means of strain gauge plethysmography, measurements were taken of the relative variations of volume and amplitude of the pulse waves in the hallux and of blood flow in the calf. After administration of the drug, a number of phenomena were observed, the most notable of which was a rapid and intense shift of blood from skin to muscle, followed by an increase in the global perfusion of the limb. Considering the physio-pathological importance of regional blood redistribution between skin and muscle and the high frequency rate of skin lesions in vascular diseases of the limbs, the possibility of evaluating, with a practical, non-invasive technique, the effects of drugs at the skin level is of great interest.

The importance of a "compression-mobilization" association in order to attain a correct therapeutical procedure is stressed. The authors then report the results of a study conducted on patients affected by varices to establish the efficacy of a treatment by means of elastic stockings with graduated compressive pressure and the efficacy of reflex-rheography as a noninvasive, economical and easy-to-use method for the assessment of the variations in venous return flow produced by the association of muscular activity and elastocompression.

The edge states of Topological Insulators (TI) are protected against backscattering, thanks to the topological properties arising from their band structure. Coupling a TI to a superconductor (S) can induce unconventional effects, including the creation of Majorana bound states (MBS). The fabrication of coplanar hybrid devices is a fundamental step to pave the way to the understanding of proximity effects in topologically non-trivial systems, and to a large variety of experiments aimed at the possible detection of MBS. We discuss the feasibility and some relevant properties of Al-Bi2Se3-Al coplanar proximity devices. Special attention is devoted to the design of the junction, aimed at enhancing the coupling between the electrodes and the TI.

By using nanolithography and a soft etching procedure, we have realized YBa2Cu3O7-x/La0.7Sr0.3MnO3 (YBCO/LSMO) nanowires, with cross sections down to 100 x 50 nm(2) that ensure the cover age of areas up to 10 x 30 mu m(2). The LSMO layer acts as a capping for YBCO, minimizing the degradation of the superconducting properties taking place during the patterning; moreover, as a ferromagnetic manganite, it is expected to accelerate the relaxation dynamics of quasiparticles in YBCO, making such a system potentially attractive for applications in superconducting ultrafast optoelectronics. The reproducibility of the values of the critical current densities measured in different devices with the same geometry makes our nanowires ideal candidates for photoresponse experiments. First measurements have shown a satisfactory photoresponse from YBCO/LSMO devices.

We present femtosecond pump-probe spectroscopy studies of time-resolved optical reflectivity of all-oxide YBa2Cu3O7/La0.7Sr0.3MnO3 (YBCO/LSMO) superconductor/ferromagnet (S/F) bilayers consisting of a 100-nm-thick YBCO base layer and either 10 or 35 nm LSMO cap thickness. At temperatures far below the YBCO superconducting transition T-C, samples with a 10 nm F overlayer show a photoresponse that is similar to, but faster than, pure-YBCO, 100-nm-thick reference samples, while close to T-C and above (up to similar to 160 K) we observe a signature of both the electronic and spin response that cannot be interpreted as an incoherent sum of contributions from the two layers. The photoresponse of the S/F structures with the 35-nm LSMO layer always qualitatively follows that of the pure LSMO, but with a shorter relaxation time. In all cases, the YBCO/LSMO nonequilibrium dynamics can be modeled using a generalized multitemperature model, which is a superposition of the dynamics of the three-temperature models that are used to describe the superconductor and ferromagnet subsystems, respectively. The long term of the photoresponse signal of the S/F bilayer can be well fitted with the two characteristic relaxation times. DOI: 10.1103/PhysRevB.87.134514