Complex magnetic phase diagram of TmCu 2

The orthorhombic intermetallic compound TmCu₂ orders antiferromagnetically below T_N=6.5 K. Bulk studies indicate a complex magnetic phase diagram (MPG) in fields along the b axis. Neutron diffraction on a single crystal of TmCu₂ confirmed the complexity of the MPG. Four different antiferromagnetic (AF) phases were observed below T_N in zero magnetic field; the ground state AF1 corresponds to the squared-up AF structure with propagation vector τ₁=(5/8,0,0) and magnetic unit cell 8a×b×c. Four ferrimagnetic phases were found for B<0.5 T parallel to the b axis and a field-induced ferromagnetic phase exists for higher fields. The individual phases were identified and the MPG along the b axis is presented.