Magnetic properties of Cu[C6H2(COO)4][H3N–(CH2)2–NH3]·3H2O - A quasi-two-dimensional S = 1/2 antiferromagnet on rectangular lattice

Abstract

The analysis of specific heat, magnetic susceptibility and magnetization identified the studied compound Cu[C6H2(COO)4][H3N–(CH2)2–NH3]·3H2O as a quasi-two-dimensional S = 1/2 Heisenberg antiferromagnet on the rectangular lattice with the intrachain coupling J1/kB≈ 7.39 K and the interaction ratio R ≈ 0.44. A phase transition to a magnetically ordered state was observed in zero magnetic field at TN = 1.28 K. The analysis of magnetic specific heat in non-zero magnetic fields revealed features characteristic of the field-induced Berezinskii-Kosterlitz-Thouless phase transition theoretically predicted for ideal two-dimensional magnets. The electron paramagnetic resonance studies of Cu[C6H2(COO)4][H3N–(CH2)2–NH3]·3H2O revealed the increase of gx and gy and decrease of gz below 25 K due to the presence of dipolar coupling and the exchange anisotropy. The upturn of linewidth appearing below 30 K can be ascribed to the development of intralayer magnetic correlations.