Single pair of multi-Weyl points in nonmagnetic crystals

Topological semimetal states having the minimal number, i.e., only a single pair, of Weyl points are desirable for study effects associated with chiral topological charges. So far, search such is focused on magnetic spinful systems. Here, we find that nonmagnetic spinless systems can host class single-pair-Weyl-point (SP-WP) states, where two located at high-symmetry time-reversal-invariant momenta. We identify 32 candidate space groups and show charge each point in SP-WP state must be an even integer. Besides achieving far separated momentum space, making physics individual better exposed. The large separation combined lead to extended surface Fermi loops non-contractible winding topology Brillouin zone torus, distinct from conventional semimetals. confirm our proposal phonon spectra concrete materials TlBO$_2$ KNiIO$_6$. Our finding applies wide range systems, including electronic, phononic, various artificial It offers new direction ideal platforms particles.