BPZT HBARs for Magnetoelastic Stress Generation at GHz Frequencies

Abstract

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Energy-efficient spin injector into semiconductors driven by elastic waves

“…Expressing u max via the maximal strain ε max in the acoustic wave, we obtain W = α 1 K 2 1 2 Aρc 3 ε 2 max . For the device with A < 25 µm 2 and K 2 = 12% [36], which is driven by a transverse (α = 4) or longitudinal (α = 1) wave with ε max = 10 −4 , the calculation yields W < 2 mW. This value is much smaller than the lowest power consumption W ≈ 25 mW of the spin injector driven by the microwave magnetic field [20].…”

“…, where K 2 is the electromechanical transduction efficiency of the piezoelectric transducer [36], c is the velocity of the generated longitudinal or transverse acoustic wave, and A denotes the dynamically strained area of the ferromagnetic film having the mass density ρ. Expressing u max via the maximal strain ε max in the acoustic wave, we obtain W = α 1 K 2 1 2 Aρc 3 ε 2 max .…”

“…For this reason, alternative spin pumping techniques have been studied during the past decade, one of which is based on the excitation of magnetization dynamics in ferromagnets by injected elastic waves [25][26][27][28][29][30][31][32][33][34]. Since such waves can be generated by a piezoelectric transducer coupled to the ferromagnet and subjected to an ac electric field, the power consumption of elastically driven spin injectors is expected to be comparatively low [34][35][36]. The experimental and theoretical studies have demonstrated an efficient generation of spin currents in normal metals by surface and bulk acoustic waves, but the strain-driven spin pumping into semiconductors was not investigated so far.…”

Microwave Properties of Ba-Substituted Pb(Zr0.52Ti0.48)O3 after Chemical Mechanical Polishing

“…CMP and cleaning processes.-The BPZT samples were polished in a Mecapol E460 system using an Optivision 4548 soft pad and a silica (SiO 2 ) abrasive slurry (ILD3013, pH [10][11]. Two conditions were used for the rotation speed of the top (head) and bottom (table) plates as well as for the applied down force.…”

“…for ultrasound transducers [7][8][9] or high-frequency bulk acoustic resonators. 10,11 Furthermore, PZT has been proposed as piezoelectric material in multiferroic composites [12][13][14] for microelectronic applications. [15][16][17][18] However, a key limitation of PZT thin films in such applications can be the reduced dielectric (and therefore piezoelectric) response at high frequencies, especially in the microwave regime, due to dielectric relaxation and large losses.…”