Low-temperature ESR spectrum in a powder sample of Cu(C10H8N2)(H2O)2SO4

The ESR spectrum of a powder sample of the metal-organic complex Cu(C10H8N2)(H2O)2SO4 is investigated in the temperature interval 2–30 K. It is found that the orbital ground level of the Cu2+ ion in this compound is the Kramers doublet |x2−y2〉. The temperature dependences of the effective g-factor components and of the resonance linewidth ΔH of individual powder particles are obtained. Low-temperature broadening of the resonance line connected with short-range magnetic order in the system is observed. An estimate of the value of the exchange coupling in the magnetic system is made.