  We present high-temperature ferromagnetism and large magnetic anisotropy in
heavily Fe-doped n-type ferromagnetic semiconductor (In1-x,Fex)Sb (x = 20 -
35%) thin films grown by low-temperature molecular beam epitaxy. The
(In1-x,Fex)Sb thin films with x = 20 - 35% maintain the zinc-blende crystal and
band structure with single-phase ferromagnetism. The Curie temperature (TC) of
(In1-x,Fex)Sb reaches 390 K at x = 35%, which is significantly higher than room
temperature and the highest value so far reported in III-V based ferromagnetic
semiconductors. Moreover, large coercive force (HC = 160 Oe) and large remanent
magnetization (Mr/MS = 71%) have been observed for a (In1-x,Fex)Sb thin film
with x = 35%. Our results indicate that the n-type ferromagnetic semiconductor
(In1-x,Fex)Sb is very promising for spintronics devices operating at room
temperature.
