Electrical transport properties of single-crystalCaB6,SrB6, andBaB

Jolanta Stankiewicz

¹

,

Priscila Rosa

²

,

P. Schlottmann

³

et al.

Abstract

The electrical resistivity and Hall effect of alkaline-earth-metal hexaboride single crystals are measured as a function of temperature, hydrostatic pressure, and magnetic field. The transport properties vary weakly with the external parameters and are modeled in terms of intrinsic variable-valence defects. These defects can stay either in (1) delocalized shallow levels or in (2) localized levels resonant with the conduction band, which can be neutral or negatively charged. Satisfactory agreement is obtained for electronic transport properties in a broad temperature and pressure range, although fitting the magnetoresistance is less straightforward and a combination of various mechanisms is needed to explain the field and temperature dependences.

Localized magnetic moments in metallic SrB6 single crystals

“…All above results imply that the weak ferromagnetism in electron-doped SrB 6 could be brought about by intrinsic defects, and not by extrinsic contamination with ferromagnetic elements. We observe a clear correlation between resistivity, carrier concentration and defect density in our data for SrB 6 , in agreement with findings for other alkaline-earth hexaborides [33,34]. Samples with larger carrier concentration (lower resistivity) have more native defects.…”

“…Both quantities increase with increasing electron concentration in the SrB 6 samples. In addition, the values of N Sch match the concentration of one-electron localized states in the model of variable-valence defects as obtained from transport measurements on the same samples [33,34].…”

“…The resistivity of this sample varies with temperature very much as of one of CaB 6 samples reported in Ref. [34] whose defects' concentration is approximately 1×10 18 cm −3 . This is compatible with the entropy excess found in Ref.…”

“…Additional measurements on a BaB 6 single crystal have been carried out for comparison purposes. The electrical transport properties of these samples have been previously carefully characterized and accounted for by a variable-charge defect model [33,34]. We discuss results of experimental specific heat measurements in the context of localized magnetic moments and electronic correlations in the low-density electron gas.…”

Electrochemical Biosensor Composed of Silver Ion‐Mediated dsDNA on Au‐Encapsulated Bi2Se3 Nanoparticles for the Detection of H2O2 Released from Breast Cancer Cells

“…Bismuth selenide (Bi 2 Se 3 ), a so‐called 3D TI, has exhibited very promising properties like Dirac plasmons, thermoelectric behavior, photothermal‐conversion ability, and unique electrical conductivity because of the existence of a single‐surface Dirac cone and a six‐valley degeneracy . Possessing a sound biocompatibility, Bi 2 Se 3 has been employed for clinical applications such as cancer radiation therapy and imaging, as well as biomarker detection and diagnosis in the forms of nanoparticles (NPs) and nanosheets .…”