  Nematic superconductivity is a novel class of superconductivity characterized
by spontaneous rotational-symmetry breaking in the superconducting gap
amplitude and/or Cooper-pair spins with respect to the underlying lattice
symmetry. Doped Bi2Se3 superconductors, such as CuxBi2Se3, SrxBi2Se3, and
NbxBi2Se3, are considered as candidates for nematic superconductors, in
addition to the anticipated topological superconductivity. Recently, various
bulk probes, such as nuclear magnetic resonance, specific heat,
magnetotransport, magnetic torque, and magnetization, have consistently
revealed two-fold symmetric behavior in their in-plane magnetic-field-direction
dependence, although the underlying crystal lattice possesses three-fold
rotational symmetry. More recently, nematic superconductivity is directly
visualized using scanning tunneling microscopy and spectroscopy. In this short
review, we summarize the current researches on the nematic behavior in
superconducting doped Bi2Se3 systems, and discuss issues and perspectives.
