Magnetic iron nanoparticles in carbon nanotubes

Abstract

In this work we have studied the magnetic properties of iron nanoparticles mixed with carbon nanotubes. The ZFC-FC curves, M(H) loops and the magnetic relaxation were measured using a SQUID-magnetometer (Superconducting Quantum Interference Detector device). The ZFC and FC processes have been measured with an applied field of 100, 2000, 3000 and 5000 Oe, respectively. The ZFC curves show two peaks which may correspond to two different blocking temperatures. The energy barriers distribution was studied from the derivative of the difference between ZFC and FC curves with respect to temperature . Isothermal hysteresis loops M(H) show a higher coercitivity and irreversability with decreasing temperature. The magnetic relaxation measurements were performed down to 2K.The magnetic viscosity shows a linear dependence with temperature. Moreover we have also measured the complex permittivity in the frequency range of 200 MHz and 20 GHz and real and imaginary components of the magnetic susceptibility between 2-300K when 10 Hz and 1000 Hz frequencies were applied