Interplay between spin-glass clusters and geometrical frustration

Fabio Zimmer (1) , Cintia Silva (1) , Sergio Magalhaes (2, 3) , Claudine Lacroix (4)

1 Departamento de Física
2 Instituto de Fisica
3 U.F. S.M.
4 NEEL - TMC - Théorie de la Matière Condensée

The presence of spin-glass (SG) order in highly geometrically frustrated systems is analyzed in a cluster SG model. The model considers infinite-range disordered interactions among cluster magnetic moments and the J1−J2 model couplings between Ising spins of the same cluster. This model can introduce two sources of frustration: one coming from the disordered interactions and another coming from the J1−J2 intracluster interactions (intrinsic frustration). The framework of one-step replica symmetry breaking is adopted to obtain a one-cluster problem that is exactly solved. As a main result we create phase diagrams of the temperature T versus intensity of the disorder J, where the paramagnetic-SG phase transition occurs at Tf when T decreases for high-J values. For low-J values, the SG order is absent for antiferromagnetic clusters without intrinsic frustration. However, the SG order can be observed within the intracluster intrinsic frustration regime even for lower intensity of disorder. In particular, the results indicate that the presence of small clusters in geometrically frustrated antiferromagnetic systems can help stabilize the SG order within a weak disorder.

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Fabio Zimmer, Cintia Silva, Sergio Magalhaes, Claudine Lacroix. Interplay between spin-glass clusters and geometrical frustration. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2014, 89 (2), pp.02210. ⟨10.1103/PhysRevE.89.022120⟩. ⟨hal-00949042⟩