Finite size effects in ferromagnetic 3He nano-clusters

Eddy Collin (1) , Benjamin Canals (2) , Jean-Christian Anglès d'Auriac (2) , Henri Godfrin (1)

1 NEEL - UBT - Ultra-basses températures
2 NEEL - TMC - Théorie de la Matière Condensée

3He adsorbed on Graphite enables to create model 2D ferromagnetic Heisenberg systems. The exchange énergies are of the order of 2mK, typical sizes on the order of a thousand spins. By adding 4He (which is non magnetic) to the system, one can tune the effective size of one ferromagnetic domain. Up to now, the theoretical tools available did not allow a quantitative understanding of themagnetism of these clusters. For the first time, "engineered" ferromagnetic nano-clusters are compared to accurate theoretical models in order to understand the finite size effects. The experimental magnetization of a cluster of about 16 spins is compared to exact diagonalization and Monte-Carlo simulations based on the Heisenberg Hamiltonian.

Mots clés: ferromagnetism; nano-clusters; NMR

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

Eddy Collin, Benjamin Canals, Jean-Christian Anglès d'Auriac, Henri Godfrin. Finite size effects in ferromagnetic 3He nano-clusters. Journal of Physics: Conference Series, 2009, 150, pp.042018. ⟨10.1088/1742-6596/150/4/042018⟩. ⟨hal-00920136⟩