State diagram of nanopillar spin valves with perpendicular magnetic anisotropy

Sylvain Le Gall (1) , Julien Cucchiara (1) , Matthias Gottwald (1) , Christelle Berthelot (1) , Charles-Henry Lambert (1) , Yves Henry (2) , D. Bedau (3) , Daniel Gopman (3) , H. Liu (3) , Andrew D. Kent (3) , Johnatan. Z. Sun (4) , Weiwei Lin (5) , Dafiné Ravelosona (5) , Jordan A. Katine , Eric E. Fullerton (6) , Stéphane Mangin (1)

1 IJL - Institut Jean Lamour
2 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
3 Department of Physics [New York]
4 IBM T. J. Watson Research Centre
5 IEF - Institut d'électronique fondamentale
6 Center for Memory and Recording Research

The spin-torque switching of metallic nanopillar spin valves showing strong perpendicular anisotropy are studied. The magnetic states of the layers depend on extrinsic parameters such as the magnetic field and the dc current applied to the device. A state diagram presents a comprehensive graph of the role of those parameters on the spin-valve magnetic response. After explaining how state diagrams can be built and the different possible representation, experimental state diagrams are studied for perpendicular devices and the influence of lateral size, temperature, and field orientation are shown. An analytical model of a purely uniaxial system is presented. It is shown that this simple model does not properly reflect the experimental results, whereas if the symmetry is broken a qualitative agreement is obtained. Finally, the possible origins of the symmetry break are discussed in light of an analytical model and numerical simulations.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Sylvain Le Gall, Julien Cucchiara, Matthias Gottwald, Christelle Berthelot, Charles-Henry Lambert, et al.. State diagram of nanopillar spin valves with perpendicular magnetic anisotropy. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012, 86, pp.014419. ⟨10.1103/PhysRevB.86.014419⟩. ⟨hal-01579276⟩