Linear magnetoelastic coupling and magnetic phase diagrams of the buckled-kagomé antiferromagnet Cu3Bi(SeO3)2O2Cl

Single crystals of Cu₃Bi(SeO₃)₂O₂Cl were investigated using high-resolution capacitance dilatometry in magnetic fields up to 15 T. Pronounced magnetoelastic coupling is found upon evolution of long-range antiferromagnetic order at T_N = 26.4 (3) K. Grüneisen analysis reveals moderate effects of uniaxial pressure on T_N, of 1.8(4) K/GPa, - 0.62 (15) K/GPa and 0.33(10) K/GPa for p‖ a, b, and c, respectively. Below 22 K Grüneisen scaling fails which implies the presence of competing interactions. The structural phase transition at T_S = 120.7 (5) K is much more sensitive to uniaxial pressure than T_N, with strong effects of up to 27(3) K/GPa (p‖ c). Magnetostriction and magnetization measurements reveal a linear magnetoelastic coupling for B‖ c below T_N, as well as a mixed phase behavior above the tricritical point around 0.4 T. An analysis of the critical behavior in zero-field points to three-dimensional (3D) Ising-like magnetic ordering. In addition, the magnetic phase diagrams for fields along the main crystalline axes are reported.