High-Frequency Measurements of the Effective Spin-Spin Interactions in Tb(OH)3

Publisher Website
Google Scholar
Abstract
Measurements have been made of the field dependence of the differential susceptibility of Tb(OH)3 at temperatures between 4.5° and 16°K and dc fields up to 1 kOe, using measuring frequencies between 2 and 4 MHz. Following the method of Casimir and du Pré the results were combined to derive the temperature variation of the zero field magnetic specific heat per spin CM/R and this was fitted to an asymptotic expansion of the form CM/R = C2/T2+C 3/T3+···. Subtracting small contributions to C2 from hyperfine and crystal field effects, it was thus possible to find the leading specific heat term due to interactions between the Tb3+ ions: C2int = 0.93±0.03(°K)2 and C3int = 1.6±0.6(°K)3. Combining these values with earlier optical, thermal, and magnetic estimates of the low temperature excitations and Curie‐Weiss constant, the predicted Ising form for the interactions could be verified and values for the nondipolar interaction constants between the first, second, and third nearest neighbors determined. The analysis indicates that the ferromagnetic ordering in Tb(OH)3 is dominated by the nondipolar next‐nearest‐neighbor interactions, but there are a number of other terms both ferromagnetic and antiferromagnetic in sign which are comparable in strength. Possible consequences of the competing interactions are discussed.

This publication has 10 references indexed in Scilit: