The family of spinel compounds of which CdCr 2 Se 4 is the prototype has been found to be simultaneously ferromagnetic and semiconducting. Numerous experiments reveal, moreover, that the electronic states in these materials are strongly coupled to the degree of magnetic order. The interaction between the electronic transport and the magnetic state offers the exciting possibility of constructing electronic devices having magnetic control. This paper presents a review of literature on the magnetic, crystallographic, electrical transport, and optical properties of the chromium chalcogenide spinels as they relate to device applications. The prospects of realizing novel devices utilizing these properties are examined.

Semiconducting ferromagnetic spinels

An annotated literature survey covering major development in the area of microwave ferrite materials and devices for the period 1968-1974 is presented.

Annotated literature survey of microwave ferrite materials and devices

Spin wave amplification by a radiation field in free-carrier magnetic semiconductors

Effect of an intense laser field on the magnon damping in free carrier magnetic semiconductors

Quantitative calculation of the effect of two-magnon scattering on parallel-pump instability thresholds

The rather simple magnetic structure of the ferromagnetic insulator CdCr2Se4 makes it an attractive substance for the study of magnetic relaxation mechanisms in general, but in particular those mechanisms of importance in the vicinity of the ordering temperature. The ferromagnetic relaxation has been studied here by means of both FMR and high‐power parallel‐pump techniques. Using the latter technique, the intrinsic spin‐wave linewidth was measured up to temperatures within a few degrees of the Curie temperature. Near the Curie temperature the linewidth diverges as (T0‐T)−1 with T0=133°K. This value of T0 is in close agreement with our measured value of the Curie temperature 130°K. At low temperatures, up to 30°K, the relaxation appears to result from two‐magnon coupling of the k=0 mode to modes of higher k, which relax by the three‐magnon confluence process.

J. P. Sage

Papers

Spin‐Wave Relaxation in Ferromagnetic CdCr2Se4