  The defect induced magnetism has initiated a lot of interest in field of
spintronics. In this regard, SiC is a promising material because of its unique
properties under extreme conditions. Hence it will be very much interesting to
investigate the interaction between defects and itinerant carrier in doped SiC
for spintronics application. We report the structural stability and magnetic
interaction in Cr doped 3C-SiC synthesized by Thermal Plasma Technique. The EPR
spectrum of undoped 3C-SiC shows a sharp resonance line corresponding to
$g=2.00$ associated with the defects present in the system. Anomalous
temperature evolution tendency of the relative intensity of EPR spectra can be
attributed to magnetically correlated defects in the host matrix. For the first
time we report the detailed quantitative analysis of X-band and Q-band EPR
study in Cr doped 3C-SiC which reveals that Cr can be in multivalent state. The
non monotonous variation of Longitudinal Mode (LO) of the Raman spectra has
been explained based on the interaction between carriers and surface plasmon
using Longitudinal optical plasmon coupling model (LOPC). The carrier density
calculated by using LOPC fit with experimental data varies from
$1.8\times10^{15}$ to $4.2\times10^{17}$ cm$^{-3}$. Room temperature magnetic
measurements exhibit ferromagnetic behavior with non-zero coercivity for all
the samples up to 7 T field. We, for the first time, show the Curie temperature
to be above 760 K. Quantitative analysis of magnetic interaction validates the
applicability of Bound Magnetic Polaron Model (BMP) which probably arises from
the exchange interaction of Cr$^{3+}$ ions with related (Si, C) defects. The
polaron density estimated from the BMP fit agrees well with the carrier density
obtained from the line shape fitting of Raman spectra.
