ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We demonstrate a new and versatile method to measure, on a nanometric scale directly, the magnetostrictive properties during the magnetization process to saturation, using a modified scanning tunneling microscope (STM). Both positive and negative magnetostrictive amorphous as-quenched wires have been studied. The studied samples are single pieces of amorphous wires typically 125 μm in diameter and 10–15 mm long. The magnetostriction data are then correlated with the longitudinal magnetization process, measured by a conventional induction technique and by SQUID magnetometry. The longitudinal magnetization process measurements have been performed in the same wires used in the STM studies. The field dependence of the magnetostriction helps to discern the operative magnetization process in the wires. In a 12-mm-long Co-based amorphous wire we observe a continuous rotation of the magnetization from zero field to saturation. The field dependence of the magnetization is a linear process reaching a value of about 5100 G at 8 Oe applied field. The magnetostrictive process for the same wire measured with a STM shows a continuous shrinking of the samples as a function of the applied field, reaching a value of −280 A(ring) for 8 Oe applied field. The obtained δl/l||sat, −2.3×10−6, agrees well with reported values of the saturation magnetostriction constant for this wire. In a 15-mm-long Fe-based amorphous wire we observe a more complicated field dependence of both the magnetization and the magnetostriction processes from zero-field to saturation.The longitudinal magnetization saturates at about 14000 G for 60 Oe applied field. The magnetostrictive process for the same wire measured with STM shows an elongation onset at about 1 Oe, pointing unambiguously to a 180° domain wall movement as the operative magnetization process below this field value. The field dependence of the magnetostriction saturates at about +5000 A(ring) for 60 Oe applied field. The obtained δl/l||sat, about +3.3×10−5, is again consistent with reported values of the saturation magnetostriction constant. Thus the STM approach to determine λ, on an A(ring) length scale, gives us a distinct great advantage in studying the magnetization process towards saturation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.358077
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