2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/27849Small ferromagnets and anti-ferromagnets with an easy-plane anisotropy have a ground to first excited state (tunnel) splitting which is quasi-periodic in the magnitude of a field applied perpendicular to a principal anisotropy axis. The associated oscillations in thermodynamic quantities might be used to prove the existence of a coherent ground state even when the tunnel splitting itself cannot be directly detected.4 pages, 3 figures as separate eps filesCondensed Mattertext