3 research outputs found
Observation of a superparamagnetic breakdown in gadolinium chloride filled double-walled carbon nanotubes
In this article, the magnetic properties of gadolinium chloride-filled double-walled carbon nanotubes (GdCl3@DWNTs) in the temperature range 2-300 K are explored. The temperature-dependent phonon frequencies of the G-band were studied from 80-300 K to investigate the effect of temperature on the magnetic ordering. Temperature-dependent susceptibility measurements show that the GdCl3@DWNTs sample has a pronounced superparamagnetic phase from 83 K. The temperature dependence of the G-band frequency for filled tubes exhibited a distinct difference compared to pristine nanotubes, where a sharp phonon hardening at low temperatures was observed. A correlation between the onset temperature of superparamagnetism and the abrupt G-band phonon hardening in the filled tubes was verified. GdCl3@DWNTs were characterized by a finite remnant magnetization at 300 K which decreased as the temperature was lowered because of the presence of the discontinuous magnetic nanoparticles, providing a superparamagnetic contribution characterized by an S-shaped non-saturating hysteresis loop at 2 K. Remarkably, the onset of superparamagnetism, marked by the bifurcation point, occurred at roughly the same temperature where the G-band phonon frequency showed a pronounced hardening at approximately 80 K, indicating a close correlation between phonon modes and spin clusters
Combined Spectroscopy and Electrical Characterization of La:BaSnO Thin Films and Heterostructures
For La-doped BaSnO thin films grown by pulsed laser deposition, we
combine chemical surface characterization and electronic transport studies to
probe the evolution of electronic states in the band structure for different
La-doping content. Systematic analyses of spectroscopic data based on fitting
the core electron line shapes help to unravel the composition of the surface as
well as the dynamics associated with increasing doping. This dynamics is
observed with a more pronounced signature in the Sn 3d core level, which
exhibits an increasing asymmetry to the high binding energy side of the peak
with increasing electron density. The present results expand the current
understanding of the interplay between the doping concentration, electronic
band structure and transport properties of epitaxial La:BaSnO films.Comment: 7 Figures, 4 Tables in manuscript; and 6 Figures and 1 Table in the
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