title: Driving ferromagnetic resonance frequency of FeCoB/PZN-PT multiferroic heterostructures to Ku-band via two-step climbing: composition gradient sputtering and magnetoelectric coupling.
abstract: RF/microwave soft magnetic films (SMFs) are key materials for miniaturization and multifunctionalization of monolithic microwave integrated circuits (MMICs) and their components, which demand that the SMFs should have higher self-bias ferromagnetic resonance frequency fFMR, and can be fabricated in an IC compatible process. However, self-biased metallic SMFs working at X-band or higher frequency were rarely reported, even though there are urgent demands. In this paper, we report an IC compatible process with two-step superposition to prepare SMFs, where the FeCoB SMFs were deposited on (011) lead zinc niobate-lead titanate substrates using a composition gradient sputtering method. As a result, a giant magnetic anisotropy field of 1498 Oe, 1-2 orders of magnitude larger than that by conventional magnetic annealing method, and an ultrahigh fFMR of up to 12.96 GHz reaching Ku-band, were obtained at zero magnetic bias field in the as-deposited films. These ultrahigh microwave performances can be attributed to the superposition of two effects: uniaxial stress induced by composition gradient and magnetoelectric coupling. This two-step superposition method paves a way for SMFs to surpass X-band by two-step or multi-step, where a variety of magnetic anisotropy field enhancing methods can be cumulated together to get higher ferromagnetic resonance frequency.
authors.affiliation: College of Physics, and Key Laboratory of Photonics Materials and Technology in Universities of Shandong, Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China.
authors.forename: Shandong
authors.initials: S
authors.lastname: Li
authors.affiliation: College of Physics, and Key Laboratory of Photonics Materials and Technology in Universities of Shandong, Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Xue
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Jenq-Gong
authors.initials: JG
authors.lastname: Duh
authors.affiliation: College of Physics, and Key Laboratory of Photonics Materials and Technology in Universities of Shandong, Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Du
authors.affiliation: College of Physics, and Key Laboratory of Photonics Materials and Technology in Universities of Shandong, Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.affiliation: College of Physics, and Key Laboratory of Photonics Materials and Technology in Universities of Shandong, Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wan
authors.affiliation: College of Physics, and Key Laboratory of Photonics Materials and Technology in Universities of Shandong, Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Physics, School of Science, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Yueguang
authors.initials: Y
authors.lastname: Lü