Magnetic and carrier transport properties of Mn-doped p-type semiconductor LaCuOSe:: An investigation of the origin of ferromagnetism

LaCuOSe is a wide band gap p-type semiconductor in which high density positive holes can be doped to exhibit degenerate conduction. These features should allow room-temperature ferromagnetism in a dilute magnetic semiconductor (DMS), which follows a theoretical prediction [T. Dietl et al., Science 287, 1019 (2000)], yet to be realized. A weak ferromagnetic response is observed in both bulk and thin epitaxial film samples of Mn-doped LaCuOSe with hole concentrations of similar to 10(20) cm(-3). However, the observed small magnetization (mu(B) per Mn ion of less than unity) is reasonably explained by the inclusion of 0.2 mol % of LaMnO3 and 0.1 mol % of Mn3O4, which were quantitatively analyzed in the bulk sample using highly sensitive x-ray diffractometry, i.e., Mn-doped LaCuOSe did not exhibit ferromagnetism due to the low solubility limit of Mn in LaCuOSe (< 0.5 mol %). This result demonstrates the importance of complementary characterization using both thin film and bulk samples for studying DMSs. (c) 2006 American Institute of Physics.