High-frequency ESR studies of colossal magnetoresistance system Cu(Cr1−xZrx)2S4

Abstract The magnetic properties of colossal magnetoresistance materials Cu(Cr 1− x Zr x ) 2 S 4 have been studied by the ESR measurements. A single ESR absorption line which has a Lorentzian shape was observed at high-temperatures for x =0.50. The estimated g -value is 1.98 at 198 K, which well agrees with the g -value of the free ion of Cr 3+ . With decreasing temperature, the absorption at high-temperatures splits into two absorptions below 100 K. As a possible mechanism, we suggest the coexistent magnetic states of ferromagnetism and paramagnetism for x =0.50. Any qualitative differences have not been observed in the ESR measurements for the sample with 0.45⩽ x ⩽0.60. This fact indicates that the magnetic state does not change upon Zr substitution for x =0.50 in the range of at least ±0.05.