Direct current effects on high-frequency properties of patterned permalloy thin films

Hanqiao Zhang, Axel Hoffmann, Ralu Divan, Pingshan Wang

Research output: Contribution to journalArticlepeer-review


We have investigated experimentally direct current (dc) effects on high-frequency properties of two different permalloy (Py) submicrometer patterns of 0.24 μm and 0.55 μm width, 10 μm length, and 100 nm thickness. The natural ferromagnetic resonance (FMR) frequencies for the two samples are about 8.5 and 11.5 GHz. A 50 mA dc produces a FMR frequency reduction of about 1 GHz in both samples. We extracted susceptibility spectra for the samples from the measurement data. We studied inductance variations of Py embedded transmission lines for different dc levels. With 50 mA dc, the operational frequencies of the inductances decreased by 9% and 12.5%. We also tested effects of magnetic fields generated by external magnets on the submicrometer patterns for comparison. To obtain the same magnetization rotation angle, the external magnetic field needs to be about five times larger than the Ampere field created by the direct current. This behavior is unique and may be associated with the increased thermal energy from the Joule heating effects.

Original languageEnglish (US)
Article number5326441
Pages (from-to)5296-5300
Number of pages5
JournalIEEE Transactions on Magnetics
Issue number12
StatePublished - Dec 2009
Externally publishedYes


  • DC current effects
  • High-frequency property
  • Patterned permalloy thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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