Field-induced gap formation in Yb4As3

The field-induced gap observed in the specific heat of Yb4As3 is interprete d as being due to the effective staggered field introduced hy the alternati ng g-tensor and alternating Dzyaloshinsky- Moriya interactions. This mechan ism also provides a natural explanation for the anomalous increase of magne tic susceptibility at low temperatures. A specific prediction is made for t he dependence of the gap on the field direction.