8 research outputs found
Role of Laser Excitation Wavelength and Power in the Fano Resonance Scattering in RFe0.50Cr0.50O3 (R = Sm, Er, and Eu): A Brief Raman Study
No full textHere
in the present report, we have extensively studied the impact
of the excitation laser wavelength and laser power on the Raman spectrum
of mixed Fe-Cr-based rare-earth perovskites. Resonant and excitation
laser power experiments carried out for these samples suggest the
orbital-mediated lattice rearrangement because of electronic excitation
from Cr3+(d3)-O2–-Fe3+(d5) ions, which results
in an antiresonance dip around 600 cm–1. The presence
of an antiresonance dip even at low laser power is ascribed to Fano
interference between the electronic continuum and phonons. Furthermore,
with increasing the laser power, the Raman modes show a systematic
red shift and asymmetrically broadened Raman lines, which is understood
in terms of laser-induced heating effects. Consequently, it also upraises
a question about the intrinsic nature of Fano resonance observed for
a sample, because it may have laser-induced origin too. Therefore,
the present study provides an important outcome emphasizing the high
sensitivity of Raman measurements, wherein the laser power of the
incident photons plays a major role such that it can even perturb
the original features of samples
Magneto-resistance in pristine and irradiated TaAs2
No full textHere we report the single crystal synthesis, characterization and the systematic study of the magneto-transport and magnetization measurements up to a magnetic field of 14 T and down to 3 K from room temperature in the semimetal TaAs2. By experiments on magneto-transport in pristine and irradiated samples, it is inferred that the turn on temperature behavior in the resistivity measurements is better analyzed based on Kohler’s rule, rather than as arising due to a metal insulator transition. The absence of negative longitudinal magneto-resistance in TaAs2 has been confirmed by careful measurements on both pristine and irradiated samples. The low energy ion irradiation altered the surface states that were reflected in the suppression of de Haas van Alphen oscillations. Hall analysis reaffirmed the role of multiple carriers, electrons and holes, in the magneto-transport of this class of materials
