ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
SmMn2Ge2 is a layered ferromagnet with unusual magnetic and electrical properties. In some regards it is a natural analog to artifically layered thin film materials, and its study can provide valuable insights. SmMn2Ge2 is ferromagnetic from 0 to 90 K, with easy axes parallel to the (110) directions (FM1 state). Between 90 and 150 K it is antiferromagnetic, and from 150 K to Tc (340 K) it is again ferromagnetic, with an easy axis parallel to the (001) direction (FM2 state). We have used a continuous recording torque magnetometer to monitor the energy surface of SmMn2Ge2 as a function of temperature. We have found that the moments are parallel to (110) in the AFM state, and that the anisotropy constant varies continuously, i.e., that K→0 at the easy-axis transition, which is found to be at essentially the same temperature as the zero-field AFM/FM2 transition. The FM1/AFM and AFM/FM2 transition temperatures can be varied over a wide range by substitution on the various sites. Substitution of Y or Gd on the Sm site increases TAFM/FM2 strongly, and is found to increase the temperature of the easy axis transition, but not by precisely the same factor. Substitution of a small amount of Cr on the Mn site decreases TAFM/FM2 but appears to have no effect on the easy-axis transition. M-H curves and M-T curves taken in a vibrating sample magnetometer and in a SQUID magnetometer provide corroborating evidence for these conclusions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.356910
