  We predict the existence of a new metastable magnetization state in a
single-domain nanomagnet with uniaxial shape anisotropy. It emerges when a
spin-polarized current, delivering a spin-transfer-torque, is injected into the
nanomagnet. It can trap the magnetization vector and prevent
spin-transfer-torque from switching the magnetization from one stable state
along the easy axis to the other. Above a certain threshold current, the
metastable state no longer appears. This has important technological
consequences for spin-transfer-torque based magnetic memory and logic systems.
