Ground state candidate and thermodynamics of Apamea spin ice.

Shevchenko, Yuriy; Strongin, Vladislav; Trefilov, Ivan; Lobanova, Eliza; Ovchinnikov, Pavel; Ternovoi, Nikita; Cherkasov, Mihail; Nefedev, Konstantin · Phys Rev E · 2026

basic_science · Level V

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Abstract

We consider the dipolar spin ice on a 2D Apamea lattice whose geometry is derived from the square spin ice. We propose ground-state candidate configurations and show that not all vertices are in energetically favorable states. There is no macroscopic degeneracy of the ground-state candidate. By using the numerical Metropolis method, we demonstrate the existence of three phases of magnetic order and explain their origins. A good agreement between the Metropolis and XMCD experiment is demonstrated, and the improved Apamea lattice geometry for the experimental observation of the dynamics in the ordered state is proposed.