Manipulation of the altermagnetic order in CrSb via crystal symmetry.

Crystal symmetry guides the development of condensed matter. The unique crystal symmetry connecting magnetic sublattices not only distinguishes altermagnetism from ferromagnetism and conventional antiferromagnetism but also enables it to combine the advantages of ferromagnetism and antiferromagnetism. Altermagnetic order is essentially a magnetic crystal order, determined by the magnetic-order (Néel) vector and crystal symmetry. Previous experimental studies have concentrated on manipulating the altermagnetic symmetry by tuning the Néel vector orientations. However, manipulation of the crystal symmetry, which holds great promise for manipulating the altermagnetic order, remains challenging. Here we realize the manipulation of altermagnetic order in chromium antimonide (CrSb) films via crystal symmetry. The locking between the Dzyaloshinskii-Moriya vector and the magnetic space symmetry helps to reconstruct the altermagnetic order, from a collinear Néel vector to a canted one. It generates a room-temperature spontaneous anomalous Hall effect in an altermagnet. The relative direction between the current-induced spin polarization and the Dzyaloshinskii-Moriya vector determines the switching modes of altermagnetic order, that is, parallel for the field-assisted mode in CrSb /Pt and non-parallel for the field-free mode in W/CrSb . The Dzyaloshinskii-Moriya vector induces an asymmetric energy barrier in the field-assisted mode and generates an asymmetric driving force in the field-free mode. In particular, the latter is guaranteed by the emerging Dzyaloshinskii-Moriya torque in altermagnets. Reconstructing crystal symmetry adds a new twist to the manipulation of altermagnetic order. It not only underpins the magnetic-memory and nano-oscillator technology but also inspires crossover studies between altermagnetism and other research topics.