Electron spin resonance of nanoporous carbon with embedded cobalt clusters

Abstract

Cobalt clusters were embedded into a nanoporous carbon powder (with pores about 2 nm in size) prepared from a B4C carbide powder. Electron spin resonance (ESR) measurements were carried out within a broad temperature range. At all temperatures, the ESR spectrum consisted of two overlapping resonance Lorentzian lines. The temperature dependences of the integrated intensities and linewidths and of the resonance fields were determined. A theoretical analysis of these dependences shows that they can be described in terms of the theory of a disordered magnetic medium with two spin systems with different properties.