Magnetoelectronic properties of a ferrimagnetic semiconductor: The hybrid cupromanganite CaCu3Mn4O12

RBEN WEHT; WARREN E. PICKETT

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 2002 vol. 65 p. 44151 - 44156

1098-0121

The mixed manganite cuprate CaCu3Mn4O12 is calculated, using density functional methods, to be a spinasymmetric ferrimagnetic semiconductor with a small gap. Cu (formally spin 1/2) antialigns with Mn (formally spin 3/2), and the net spin moment is 9mB , consistent with the formal spins. The valence-band maximum has Cu dxy–O ps character with spin aligned antiparallel with the net magnetization; the conduction-band minimum has the opposite spin and mixed Cu-Mn character. This spin-asymmetric gap ~1! implies a thermally induced current that is 100% spin polarized and ~2! leads to a field-induced narrowing of the energy gap. The relationship of these properties to the reported magnetoresistance is discussed.