During systematic search for high thermoelectric force in the iron base
alloys, the author's group found a new alloy which have the Heusler structure.
It consists of Fe, V and Al with the atomic ratio of 2:1:1. When V loses, the
p-type conductor with high Seebeck coefficient was formed. When V was added to
excess 25 mol%, it becomes n-type conducter with negatively large Seebeck
coefficient. The current topics in this new alloy was reviewed.