We have extensively studied the magnetic features of a heterometallic molecular trimer, ${\text{Cr}}_2\text{Cu}$. We have characterized molecular ${\text{Cr}}_2\text{Cu}$ by low-temperature ac susceptibility and specific-heat measurements and this allowed us to determine the microscopic parameters of the spin Hamiltonian. Then, we used x-ray magnetic circular dichroism to selectively probe local symmetries, electronic configuration, orbital, and spin magnetic moments of the magnetic ions. We found that at low temperatures only the ground state $S=3/2$ is occupied and the spin of Cu is found opposite to that of Cr in agreement with spin-Hamiltonian calculations.

• Received 20 August 2010

DOI:https://doi.org/10.1103/PhysRevB.82.144420