Investigating structure and physical properties of quaternary layered transition metal oxide Na2Cu2TeO6

Abstract: We investigated the crystal structure, magnetic behavior, and optical properties of the layered honeycomb compound Na2Cu2TeO6. X-ray and neutron diffraction confirmed a monoclinic structure, with Cu ions arranged in dimerized chains. Magnetic susceptibility measurements yielded a Curie-Weiss temperature significantly lower than the expected spin-only value, indicating the presence of strong antiferromagnetic interactions and enhanced quantum fluctuations. A broad maximum near 160 K in the susceptibility data is consistent with short-range one-dimensional antiferromagnetic correlations. Magnetization measurements showed negligible coercivity, and specific heat data revealed no anomalies down to 3 K. Temperature-dependent neutron diffraction showed no evidence of long-range magnetic order. Optical absorption studies using UV-Visible spectroscopy displayed a sharp absorption edge in the UV region. Tauc analysis estimated a direct optical band gap of approximately 2.10 eV, with no clear indication of an indirect transition. These observations provide insight into the interplay between structural distortions, low-dimensional magnetism, and optical behavior in Na2Cu2TeO6