Dependence of the colored frequency noise in spin torque oscillators on current and magnetic field
2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, no 9, 092405- p.Article in journal (Refereed) Published
The nano-scale spin torque oscillator (STO) is a compelling device for on-chip, highly tunable microwave frequency signal generation. Currently, one of the most important challenges for the STO is to increase its longer-time frequency stability by decreasing the 1/f frequency noise, but its high level makes even its measurement impossible using the phase noise mode of spectrum analyzers. Here, we present a custom made time-domain measurement system with 150MHz measurement bandwidth making possible the investigation of the variation of the 1/f as well as the white frequency noise in a STO over a large set of operating points covering 18-25GHz. The 1/f level is found to be highly dependent on the oscillation amplitude-frequency non-linearity and the vicinity of unexcited oscillation modes. These findings elucidate the need for a quantitative theoretical treatment of the low-frequency, colored frequency noise in STOs. Based on the results, we suggest that the 1/f frequency noise possibly can be decreased by improving the microstructural quality of the metallic thin films.
Place, publisher, year, edition, pages
2014. Vol. 104, no 9, 092405- p.
Amplitude-frequency, Measurement bandwidth, Metallic thin films, Spin-torque oscillator (STO), Spin-torque oscillators, Theoretical treatments, Time domain measurement, Tunable microwave
Other Physics Topics
IdentifiersURN: urn:nbn:se:kth:diva-144370DOI: 10.1063/1.4867257ISI: 000332729200057ScopusID: 2-s2.0-84896799716OAI: oai:DiVA.org:kth-144370DiVA: diva2:713304
FunderSwedish Foundation for Strategic Research Swedish Research Council, 2009-4190Knut and Alice Wallenberg Foundation
QC 201404222014-04-222014-04-222016-06-20Bibliographically approved