High-Field Magnetism of the Spin-1=2 Two-Leg-Ladder Antiferromagnet Cu(DEP)Cl₂ under High Pressure

We report the magnetic properties of powder samples of the two-leg-ladder antiferromagnet Cu(DEP)Cl₂ (DEP: 2,3-diethylpyradine) measured in magnetic fields of up to 40 T under pressures (P) of up to 1.7 GPa. Measured magnetic properties (magnetic susceptibility and high-field magnetization with two transition fields) at ambient P are compared with those calculated by a quantum Monte Carlo method and are well explained by the two-leg-ladder antiferromagnetic model with large rung exchange interaction (J_rung). A peak of magnetic susceptibility shifts largely to a higher temperature with a significant decrease in height, and both transition fields shift largely to higher fields at a critical pressure P_c of approximately 0.2 GPa.