Altermagnets are compensated magnets with unconvetional d, g and i-wave
spin-channel order in reciprocal space. So far the search for new altermagnetic
candidates has been focused on materials in which the magnetic unit cell is
identical to the non-magnetic one, i.e. magnetic structures with zero
propagation vector. Here, we substantially broaden the family of altermagnetic
candidates by predicting supercell altermagnets. Their magnetic unit cell is
constructed by enlarging the paramagnetic primitive unit cell, resulting in a
non-zero propagation vector for the magnetic structure. This connection of the
magnetic configuration to the ordering of sublattices gives an extra degree of
freedom to supercell altermagnets, which can allow for the control over the
order parameter spatial orientation. We identify realistic candidates MnSe2
with a d-wave order, and RbCoBr3, CsCoCr3, and BaMnO3 with g-wave
order. We demonstrate the reorientation of the order parameter in MnSe2,
which has two different magnetic configurations, whose energy difference is
only 5 meV, opening the possibility of controlling the orientation of the
altermagnetic order parameter by external perturbations.Comment: 10 pages, 4 figure