EPR line broadening and magnetic phase transitions in antiferromagnetic FeP3O9

Alvin Kie
1975 Physical Review B  
The EPR linewidths of polycrystallinesamples of antiferromagnetic ferric metaphosphate {FeP3Oq) has been measured in the range 0.01 g T -T& g 100 K (T"= 9.3 K). The widths were fitted to a Power-jaw form (T -Ta)r In t.he reduced tem-Perature range 0.03 & e & 0.7 [c=(T -T")IT"], the best fit gives y~-0.67. For a & 0.02, the change in linewidth is very slight. At high temperatures such that c & 1, far above the critical regime, we obtained y = -1.65. These results are quite similar to some recent
more » ... ilar to some recent results of Birgeneau on NiC12. Spin-flip transitions have been observed from individual crystallites in the polycrystalline samples at 4.2 ind 1.6 K. By cycling the magnetic field and temperature we obtain a signal at 4.2 K which exactly mimics the EPR signals for T & TN (T"= 9.3 K) with no sign of the spin-Qop transitions. This implies a striking hysteresis in the II-T phase diagram.
doi:10.1103/physrevb.12.1868 fatcat:sigbv3iqqnhgpc64n4a5ljwqgm