language: en

Current induced domain wall motion in Ni 80 Fe 20 nanowires with low depinning fields

Grégory Malinowski 1 , Andreas Lörincz 1 , Stephen Krzyk 1 , Philipp Möhrke 1 , Daniel Bedau 1,3 , Olivier Boulle 1 , Jan Rhensius 1,2 , Laura J. Heyderman 2 , Young Jin Cho 3 , Sunae Seo 3 and Mathias Kläui 1
1 Fachbereich Physik, Universität Konstanz,
Universitätsstrasse 10, D-78457, Germany.
2 Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut,
CH-5232 Villigen PSI, Switzerland.
3 Samsung Electronics,
San 14-1 Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do, Korea.
E-mail: gregory.malinowski@uni-konstanz.de

Abstract. In this paper, we report on domain wall motion induced by current pulses at variable temperature in 900 nm wide and 25 nm thick Ni 80 Fe 20 wires with low pinning fields. By using Ar ion milling to pattern our wires rather than the conventional lift-off technique, a depinning field as low as ∼ 2 − 3 Oe at room temperature is obtained. Comparison with previous results acquired on similar wires with much higher pinning shows that the critical current density scales with the depinning field, leading to a critical current density of ∼ 2.5 × 10 11 A/m 2 at 250 K. Moreover, when a current pulse with a current density larger than the critical current density is injected, the domain wall is not necessarily depinned but it can undergo a modification of its spin structure which hinders current-induced domain wall motion. Hence, reliable propagation of the domain wall requires an accurate adjustment of the pulsed current density.

[Current induced domain wall motion in Ni 80 Fe 20 nanowires with low depinning fields 2]

1. Introduction