2014 Publications

Interfaces anisotropy in single crystal V/Fe/V trilayer
D. Louis, I. Lytvynenko, T. Hauet, D. Lacour, M. Hehn, S. Andrieu, and F. Montaigne (2014)
J. Magn. Magn. Mater. 372, 233

Value and sign of V/Fe interface anisotropy are investigated. Epitaxial V/Fe/V/Au ultrathin films with different iron thicknesses were grown on single-crystalline (001)MgO substrate byultra-high vacuum molecular beam epitaxy. Magnetometry was used to measure magnetization and out-of-plane anisotropy field. From these values, we quantify the number of dead layers due to V/Fe or Fe/V interfaces, and compare it with the literature. We deduce that dead layers occur mostly at the bottom V/Fe interface. An average value for V/Fe and Fe/V interface anisotropy of 0 +/- 0.1 mJ/m2 (erg/cm2) was thus deduced.

Measurement of magnetization using domain compressibility in CoFeB films with perpendicular anisotropy
N. Vernier, J.-P. Adam, S. Eimer, G. Agnus, T. Devolder, T. Hauet, B. Ockert, and D. Ravelosona (2014)
Appl. Phys. Lett 104 , 122404

Here an original method is presented to map the saturation magnetization of soft ultrathin films without typical magnetomeetry method. We illustrate it to assess the compositional dependence of the magnetization of CoFeB(1 nm)/MgO films. The method relies on the measurement of the dipolar repulsion of parallel domain walls that define a linear domain. The film magnetization is linked to the field compressibility of the domain. The method also yields the minimal distance between two walls before their merging, which sets a practical limit to the storage density in spintronic devices using domain walls as storage entities.

A Single-Chain Magnet Based on {CoII 4} Complexes and Azido/Picolinate Ligands
J. Liu, M. Qu, M. Rouzières, X-M. Zhang and R. Clérac (2014)
Inorg. Chem., 53 (15), pp 7870–7875

A new homonuclear single-chain magnet self-assembles as a one-dimensional coordination network of defective dicubane {CoII4} complexes linked by single CoII ions with the assistance of azido and picolinate ligands. Dominating intrachain ferromagnetic interactions, intrinsic Ising-like CoII anisotropy, and negligible interchain magnetic interactions lead to a thermally activated relaxation time of the magnetization below 8 K. Two thermally activated regimes above and below 3.5 K are observed with the following energy barriers: Δτ1/kB = 66 K (τ0 = 3.7 × 10–11 s) and Δτ2/kB = 51 K (τ0 = 2.3 × 10–9 s), respectively. The difference between the two energy barriers of the relaxation time, 15 K, agrees well with the experimental energy, Δξ, to create a domain wall along the chain.