Metamagnetic transitions and magnetoelectricity in the spin-1 honeycomb antiferromagnet Ni2Mo3O8

Diffusive excitonic bands from frustrated triangular sublattice in a singlet-ground-state system

“…The X-ray and neutron diffraction refinements also show that nonmagnetic dopant ions like Zn 2+ prefer to occupy the tetrahedral sites 12 . Consistent with previous neutron powder diffraction work 12 , 13 , our neutron single crystal diffraction refinements find that the spins of Ni 2+ ions form a stripy AF order (Fig. 1c and d ) below T N = 5.5 K (Fig.…”

“…The two M 2+ sites have different oxygen coordination, with one site being an MO 6 octahedron and the adjacent one being an MO 4 tetrahedron. In this family, Ni 2 Mo 3 O 8 was studied as a platform to explore the physics of geometrically frustrated lattice 12 , 13 . Neutron powder diffraction experiments reveal that both the MO 6 octahedron and the MO 4 tetrahedron each form perfect triangular lattices with no inter-site disorder, and the system orders antiferromagnetically with a Néel temperature of T N = 5.5 K 12 , 13 .…”

“…In this family, Ni 2 Mo 3 O 8 was studied as a platform to explore the physics of geometrically frustrated lattice 12 , 13 . Neutron powder diffraction experiments reveal that both the MO 6 octahedron and the MO 4 tetrahedron each form perfect triangular lattices with no inter-site disorder, and the system orders antiferromagnetically with a Néel temperature of T N = 5.5 K 12 , 13 . The magnetic structure is stripe like within the Ni-O plane, and zig-zag like along the c -axis with different ordered moments for octahedral and tetrahedral Ni sites (Fig.…”

“…Here we use thermodynamic and neutron scattering experiments to study stoichiometric honeycomb lattice antiferromagnetic (AF) ordered magnet Ni 2 Mo 3 O 8 , where Ni 2+ ions form a bipartite honeycomb lattice comprised of two triangular lattices, in the tetrahedral and octahedral crystalline environment, respectively (Fig. 1a–c ) 12 , 13 . We find that CEF levels of Ni 2+ ions from both tetrahedral and octahedral environments have a nonmagnetic spin-singlet-ground state but with very different single-ion anisotropy energy scales for the two sites.…”

Band-Mott mixing hybridizes the gap in Fe2Mo3O8

“…Fe 2 Mo 3 O 8 also displays a 5 T transition to the ferrimagnetic state with an extremely large magnetoelectric coefficient [14,15]. Ni 2 Mo 3 O 8 also hosts robust magnetoelectric coupling with a field-tunable coupling mechanism [29]. Spectroscopic highlights in Fe 2 Mo 3 O 8 include (i) nonreciprocal directional dichroism [30], phonon trends across T N [26,27], and a variety of magnetic excitations in the terahertz range [31], (ii) Mössbauer to confirm the 2+ charge on the iron site [24,25], and (iii) studies of charge transfer via time-dependent optical Kerr effects [32] complemented by first-principles electronic structure calculations [20,27,33].…”