Magnetic phase diagram of a 2D quantum Heisenberg antiferromangetic compound Cu(pz)$_{2}$(ClO$_{4})_{2}$

Cu(pz)$_{2}$(ClO$_{4})_{2}$ is a 2D quantum Heisenberg antiferromagnet with an exchange strength of 17.5(5) K and a zero-field ordering temperature of 4.25 K. The ordering temperature has been found to be affected by an applied field. The phase diagram of Cu(pz)$_{2}$(ClO$_{4})_{2}$ is determined by measuring the magnetization and the in-field specific heat. The behavior of the ordering temperature can be interpreted as a field induced 2D Heisenberg to 2D XY crossover.