Crystal Growth and the Magnetic Properties of Na₂Co₂TeO₆ with Quasi-Two-Dimensional Honeycomb Lattice

Abstract

Single crystal Na 2 Co 2 TeO 6 has been successfully grown by self-flux method, and its lattice structure and basic magnetic properties were characterized. As determined by single crystal X-ray diffraction, Na 2 Co 2 TeO 6 belongs to space group P6 3 2 2 (182) with a = b = 5.2709(2) Å, c = 11.2615(15) Å, and V = 270.95 (4) Å 3 , the crystal structure is a layered honeycomb formed by CoO 6 octahedra and the TeO 6 octahedra in the center of the honeycomb layers, and the NaO 6 octahedra are between the honeycomb layers. Magnetic susceptibility measurements indicate that the single crystal sample displays a distinct anisotropic behavior and the spin parallels the honeycomb plane (ab-plane). In a lower temperature region, a series of antiferromagnetic-like (AFM-like) phase transitions were observed, which may result from the spin reorientation of Co 2+ ions. The different magnetization behavior between the polycrystalline structure and the single crystal (with the magnetic field parallel to and perpendicular to the ab-plane) reveals obvious magnetic anisotropy of single crystal Na 2 Co 2 TeO 6 . The special honeycomb planes formed by CoO 6 octahedra and the AFM interaction inter-and intra-honeycomb planes may lead to the obvious anisotropy and complicated magnetic phase transitions.

Field-induced quantum spin disordered state in spin-1/2 honeycomb magnet Na2Co2TeO6

“…1a. Their values are consistent with the previous reports [39][40][41][42][43][44] . With an increasing magnetic field, the sharp peak at T N shifts to lower temperatures and becomes broader.…”

Kitaev Spin Liquid in 3d Transition Metal Compounds

“…Other than the experimental results presented above, different scenarios have also been proposed by other groups, such as a negligible Kitaev interaction K ∼ 0 76 or AFM K > 0 77 in Na 2 Co 2 TeO 6 deduced from neutron scattering experiments. Besides, Li and his collaborators have suggested the magnetic ground state of Na 2 Co 2 TeO 6 is beyond zz1 order considering the weak but canonical ferrimagnetic behavior under magnetic field 100,120 as shown in Fig. 14(d).…”

Honeycomb layered oxides: structure, energy storage, transport, topology and relevant insights

“…Achieving the Hamiltonian given in eqn (1b) in a condensed matter system with J = 0 is considered to be the Holy Grail of topological quantum computing. 179,186 Honeycomb layered oxides consisting of alkali or coinage metal atoms sandwiched between slabs exclusively made of transition metal and chalcogen (or pnictogen) atoms, which are the prime focus of this review, typically exhibit Néel antiferromagnetic properties, [15][16][17][18][19][20][21][23][24][25][26][27][28]31,32,34,35,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][60][61][62]91 which suggests that the Heisenberg term ( J) dominates over the Kitaev term (K). Nonetheless, observing the K-QSL phase in honeycomb layered oxides based on magnetic transition atoms with 3d orbitals such as M = Co, has shown great promise due to the localised nature of the magnetic electrons which favour the chargetransfer phase 188 of the Mott insulator -a prerequisite for the realisation of the Kitaev-Heisenberg model.…”

“…8. [15][16][17][18][19][20][21][23][24][25][26][27][28]31,32,34,35,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][60][61][62]91 Another intriguing manifestation of anti-ferromagnetism is the manner in which the The magnetic transition temperatures of Na-based honeycomb layered oxides (that have mostly been subject of passionate research owing to their intriguing magnetism) has been highlighted for clarity to readers. [15][16][17][18][19][20][21][23][24][25][26][27][28]31,32,…”

“…In fact, the possibility of growing single crystals in honeycomb layered oxides (such as Na 2 Ni 2 TeO 6 , Na 2 Cu 2 TeO 6 , Na 3 Cu 2 SbO 6 and Na 2 Co 2 TeO 6 ) using high-temperature solid-state reactions has already been achieved. 24,25,39 Another fascinating pursuit will be the design of thin films from honeycomb layered oxide materials, either using molecular beam epitaxy (MBE), atomic laser deposition (ALD) or pulsed laser deposition (PLD), which will aid to accurately visualise the presence of magnetic skyrmions or any emergent topological physics that covers, inter alia, superconductivity, magneto-resistance and ferroelectricity. Moreover, an extension of the m + SR technique, namely low energy m + SR (LEM) offers the unique possibility to tune the muon implantation depth into samples from 5-500 nm.…”