A NEW-TYPE OF SPIN-GLASS IN SPIN-DENSITY-WAVE CRMN AND CRSIMN ALLOYS

Spin-density-wave (SDW) binary Cr1-xMnx (x << 0.1-4.6% Mn) and ternary (Cr + 1.3% Si)(1-x)Mn-x (x = 0.17 and 0.6% Mn) alloys are found to exhibit spin-glass behaviour, which differs however from that of a conventional spin glass in that the magnetic susceptibility chi(T) is essentially independent of temperature T between the low-temperature maximum and the Neel temperature T-N, and in that the temperature of the maximum is essentially independent of the Mn concentration. Comparison of binary and ternary alloys having the same Mn content shows that the nature of the maximum in chi(T) depends on whether or not the SDW is commensurate. A model is proposed that explains the increase in chi(T) at low temperature as resulting from pinning of the phase of the SDW to the Mn moments, which are frozen below T-N, causing frustration on the host Cr moments on the surfaces between the resultant SDW phase domains.