Stabilization of Short‐ and Long‐Range Magnetic Ordering through the Cooperative Effect of 1D [CuO4]∞ Chains and [CuO2X2] Quadrilateral in Quasi‐1D Spin‐1/2 Systems

Quasi‐1D chain antiferromagnets with reduced structural dimensionality are a rich playground for investigating novel quantum phenomena. We report the synthesis, crystal structure, and magnetism of two novel quasi‐1D antiferromagnets, β‐PbCu2(TeO3)2Cl2 (I) and PbCu2(TeO3)2Br2 (II). Their magnetic frameworks are constructed via Cu‐based quasi‐1D [Cu(2)O4]∞ zigzag chains with square‐planar [Cu(1)O2X2] (X=Cl or Br) separated among 1D chains. Specific heat measurements show λ peaks at ~9 K and ~19 K for I and II, respectively. Moreover, both broad maximums (χmax=90 K for I and 80 K for II) and small kinks (TN≈9 K for I and 19 K for II) have been observed in magnetic susceptibility measurements of I and II. Bonner–Fisher model fitting, and theoretical analyses were performed to evaluate the magnetic exchange interactions. Our experimental and theoretical results and structure‐properties relationship analysis reveal the coexistence of short‐ and long‐range magnetic ordering from the cooperative effect of 1D [CuO4]∞ chains and [CuO2X2] quadrilateral. Quasi‐1D chain antiferromagnets are considered a rich playground for investigating complex magnetic properties. We reported the synthesis, crystal structures, and magnetism of two novel copper‐based 1D chain tellurates β‐PbCu2(TeO3)2Cl2 and PbCu2(TeO3)2Br2. The short‐ and long‐range magnetic ordering is stabilized through the cooperative effect of 1D [CuO4]∞ Chains and [CuO2X2] quadrilateral in this quasi‐1D spin‐1/2 System.