title: Ultralow-current-density and bias-field-free spin-transfer nano-oscillator.
abstract: The spin-transfer nano-oscillator (STNO) offers the possibility of using the transfer of spin angular momentum via spin-polarized currents to generate microwave signals. However, at present STNO microwave emission mainly relies on both large drive currents and external magnetic fields. These issues hinder the implementation of STNOs for practical applications in terms of power dissipation and size. Here, we report microwave measurements on STNOs built with MgO-based magnetic tunnel junctions having a planar polarizer and a perpendicular free layer, where microwave emission with large output power, excited at ultralow current densities, and in the absence of any bias magnetic fields is observed. The measured critical current density is over one order of magnitude smaller than previously reported. These results suggest the possibility of improved integration of STNOs with complementary metal-oxide-semiconductor technology, and could represent a new route for the development of the next-generation of on-chip oscillators.
authors.affiliation: Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123, P. R. China. zmzeng2012@sinano.ac.cn
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Zeng
authors.forename: Giovanni
authors.initials: G
authors.lastname: Finocchio
authors.forename: Baoshun
authors.initials: B
authors.lastname: Zhang
authors.forename: Pedram
authors.initials: P
authors.lastname: Khalili Amiri
authors.forename: Jordan A
authors.initials: JA
authors.lastname: Katine
authors.forename: Ilya N
authors.initials: IN
authors.lastname: Krivorotov
authors.forename: Yiming
authors.initials: Y
authors.lastname: Huai
authors.forename: Juergen
authors.initials: J
authors.lastname: Langer
authors.forename: Bruno
authors.initials: B
authors.lastname: Azzerboni
authors.forename: Kang L
authors.initials: KL
authors.lastname: Wang
authors.forename: Hongwen
authors.initials: H
authors.lastname: Jiang