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We report the unexpected evolution, with thermal and magnetic-field (H) variations, of the interrelation between the polarization P, magnetization M, and spiral wave vector Q in CoCr2O4, which has a ferrimagnetic conical-spiral magnetic order. For example, P suddenly jumps and changes its sign at the magnetic lock-in transition (T_{L}) with thermal variation, or with isothermal variation of H (without changing its direction) at T_{L}, which surprisingly occurs without change in spiral handedness (i.e., the sign of Q). The presence of multiple spiral sublattices may be behind this unusual behavior.

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The spin, in-plane and out-of-plane orbital and magnetic dipole moments of almost purely interfacial Co atoms were directly determined for Au/2-monolayer Co nanoclusters/Au(111) by angle-dependent magnetic circular x-ray dichroism (MCXD) measurements. The field- and temperature-dependent MCXD evidences a ferromagnetic(FM)-to-superparamagnetic phase transition in single-domain clusters with decreasing size. The interfacial moments are remarkably enhanced as compared with bulk values, verifying theoretical predictions. The FM clusters show strong perpendicular magnetic anisotropy, providing promise of applications for nanoscale magnetic bits.

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