Reentrant surface anisotropy in the antiferromagnetic/ferromagnetic bilayer Mn/Co/Cu(001).
We investigated the magnetic anisotropy energy of monatomic surface-step atoms in antiferromagnetic/ferromagnetic (AF/FM) epitaxial Mn/Co bilayers grown on vicinal Cu(001) surfaces. The step-induced anisotropy of the Co/Cu(001) films was quenched upon submonolayer Mn deposition, but a reentrant uniaxial surface anisotropy was observed for Mn thickness (tMn) between 1 and 2 monolayers, which disappears for Mn thickness above 2 monolayers. In the Mn/Co/Cu(001) system, Mn films undergo a tMn-dependent transition from FM to AF in the 1-2 Mn monolayer thickness range, which entails the coexistence of FM and AF Mn phases in the film. The observation of a sizeable uniaxial anisotropy exclusively in the Mn-thickness range of coexistence of the FM and AF phases points out the crucial role of the boundaries between FM and AF regions within the Mn film. A symmetry-breaking mechanism of a magnetic type, rather than a purely geometric one, is therefore proposed as the origin of the reentrant anisotropy.
Dipartimento di Fisica, Università di Genova and CNISM, Sede Consorziata di Genova, via Dodecaneso 33, I-16146 Genova, Italy.
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M
Caminale
CNR-SPIN, Corso Perrone 24, I-16152 Genova, Italy.
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R
Moroni
Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste, Italy.
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P
Torelli
Department of Physics, National Taiwan Normal University, 116 Taipei, Taiwan.
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WC
Lin
Dipartimento di Fisica, Università di Genova and CNISM, Sede Consorziata di Genova, via Dodecaneso 33, I-16146 Genova, Italy.
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Canepa
Dipartimento di Fisica, Università di Genova and CNISM, Sede Consorziata di Genova, via Dodecaneso 33, I-16146 Genova, Italy.
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L
Mattera
CNR-SPIN, Corso Perrone 24, I-16152 Genova, Italy.
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Bisio