Regresar

Electron paramagnetic resonance in the CoIn<inf>2-2x</inf>Cr<inf>2x</inf>S<inf>4</inf> semiconductor system

Abstract:

We report electron paramagnetic resonance (EPR) measurements in the diluted magnetic semiconductor (DMS) CoIn2-2xCr2xS4, 0:05 ≤ x ≤ 1. The resonance field (HR) is obtained from the spectra, and we have found oscillations around 410 mT. When temperature decreases HR decreases also, this behavior is in agreement with a paramagnetism-ferromagnetism phase transition. In the sample x = 0.05, HR increases from ≃ 400 mT until very high values while temperature is decreasing. The linewidth ΔHpp, for all the samples increases as the temperature decreases. Near liquid nitrogen temperatures, the EPR spectra is not observed. The behavior observed below the transition temperature is explained in terms of the exchange interaction between chromium ions. The ferrimagnetic behaviour is the responsible for the poor EPR signal at low temperatures.