Effective spin- 1 2 description of transverse-field-induced random fields in dipolar spin glasses with strong single-ion anisotropy

S. M A Tabei , F. Vernay (1) , M. Gingras (2)

1 PROMES - Procédés, Matériaux et Energie Solaire
2 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille

We present analytical and numerical evidence for the validity of an effective S eff = 1 2 approach to the description of random field generation in S ജ 1, and especially for S = 1, dipolar spin-glass models with strong uniaxial Ising anisotropy and subject to weak external magnetic field B x transverse to the Ising direction. Explicitly B x-dependent random fields are shown to naturally emerge in the effective low-energy description of a microscopic S = 1 toy model. We discuss our results in relation to recent theoretical studies pertaining to the topic of B x-induced random fields in LiHo x Y 1−x F 4 magnetic materials with the Ho 3+ Ising moments subject to a transverse field. We show that the S eff = 1 2 approach is able to capture both the qualitative and quantitative aspects of the physics at small B x , giving results that agree with those obtained using conventional second-order perturbation theory.

Mots clés: number͑s͒: 7510Jm; 0550ϩq; 7510Nr; 7550Lk

Domaines: Mécanique statistique [cond-mat.stat-mech]

S. M A Tabei, F. Vernay, M. Gingras. Effective spin- 1 2 description of transverse-field-induced random fields in dipolar spin glasses with strong single-ion anisotropy. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2008, 77 (1), ⟨10.1103/PhysRevB.77.014432⟩. ⟨hal-02145564⟩