Intrinsic insulating transport characteristics in low-carrier density EuCd2As2 films

Abstract

Searching for an ideal magnetic Weyl semimetal hosting only a single pair of Weyl points has been a focal point for systematic clarification of its unique magnetotransport derived from the interplay between topology and magnetization. Among the candidates, triangular-lattice antiferromagnet EuCd2As2 has been attracting special attention due to the prediction of the ideal Weyl semimetal phase in the ferromagnetic state; however, transport properties of low-carrier density samples have remained elusive. Here, we report molecular beam epitaxy growth of EuCd2As2 films, achieving low-hole density in the range of 1015–1016 cm−3 at low temperature. Transport measurements of such low-carrier density films reveal an insulating behavior with an activation gap of about 200 meV, which persists even in the field-induced ferromagnetic state. Our work provides an important experimental clue that EuCd2As2 is intrinsically insulating, contrary to the previous prediction.