Domain-wall bowing and stability of a given wall shape are briefly reviewed. It is pointed out that Bishop’s arguments for the stable existence of severe bowing are inconclusive, since in his example, conditions at the extremities of the stretched-out wall were ignored. In contrast to the case of a weakly bowed wall, for an elongated wall, the extremities are the most likely points of instability.

A quantitative theory for the magnetostriction due to exchange interactions in metals has been developed, based on the ideas of Zener. The theory is in good agreement with the measured values for pure nickel and iron, and it explains the anomalous thermal expansion in the iron-nickel Invar alloys, as well as more complex alloys containing manganese and/or cobalt.

Superconductivity results on self doped as-cast tin telluride show a strong particle size dependence of the superconducting critical temperature (Tc, °K). The Tc of the powdered as-cast material (size ⩽ 100μ) approaches the Tc of the pressed and sintered samples. A similar but larger effect was observed in Sn0·87 Ag0·10 Te, where the Tc of the as-cast material (1·8°K) decreased to about 1°K on grinding (size ⩽ 100μ). Pressing and sintering the same material did not increase the Tc Complete Tc data on the as-cast Sn0·97−x Agx Te samples with 0·01 < × < 0·16 along with their ‘pressed and sintered’ counterpart of the same composition are presented. The effect of the magnetic impurity Mn on the Tc of Sn0·97−x−y Agx Mny Te samples was also studied by changing the parameters and the results are discussed on the basis of prevalent theories.

The low-temperature specific heat of a series of semiconductor alloys of the SnTe-MnTe system, for Mn to Sn ratios of 0 to 0.1 has been measured in the temperature range 2 to 25°K. Large anomalies are observed due, presumably, to the ordering of the Mn++ spin system. The temperature region over which these anomalies occur is roughly the region in which ferromagnetism is observed.

The origin of the large volume magnetostriction responsible for the Invar anomaly is discussed with respect to several recent theories. Magnetic and thermal expansivity measurements of Fe–Ni–Mn alloys with constant Ni/Fe ratio of 2/3 indicate qualitative agreement with Zener's theory based on competing exchange interactions. Coercive force (Hc) measurements of an Fe–Ni–Co alloy containing mixed martensite and austenite ferromagnetic phases display a maximum Hc at the Curie temperature (θγ) of the austenite which is known to display the Invar anomaly. The sharp change in the value of Hc at θγ is contrary to theories based on concentration fluctuation.