Composite Multiferroic Terahertz Emitter: Polarization Control via an Electric Field

Abstract

Electrical control of conjugate degrees of freedom in multiferroics provides the advantage of reducing energy consumption to femto-and even attojoules per switch in spintronics and memory devices. This is achieved through the development of technologies that make it possible to fabricate artificial materials with constantly improving properties. Here, we present the design, physics, and characteristics of a composite multiferroic spintronic emitter, which provides electrical control of the emitted terahertz (THz) wave polarization. The effect is due to electrical control of the magnetization in a high-quality magnetostrictive superlattice, TbCo2/FeCo, deposited on an anisotropic piezoelectric substrate. In our approach, several mechanisms are realized in the system simultaneously: the strain-mediated coupling of the magnetic and piezoelectric subsystems, which operate in the range of the spin-reorientation transition of the magnetic superlattice, and THz-wave generation in the superlattice by an optical femtosecond pulse. This provides flexibility and control of the set of parameters. We determine the magnetoelectric parameter, which is responsible for THz polarization control. Our results offer a significant fundamental insight into the physics of composite multiferroic systems that can be used for applications of multiferroicity, primarily for THz spintronic emitters. We believe that our findings represent a decisive step towards technologies for other types of spintronic and memory devices.

Spintronic emitter of terahertz radiation based on two-dimensional semiconductor tungsten diselenide

“…The peak-to-peak THz signal amplitude for Co/WSe 2 is higher than the one that was measured in our earlier study [14] for FeCo/TbCo structures. It was demonstrated in [14] that the inverse spin Hall effect, which is induced by a nonmagnetic conducting metal, is the primary mechanism of THz generation in the magnetic superlattice/non-magnetic metal structure. It should be noted that this structure design is traditional for spintronic emitters and provides the highest efficiency of THz generation.…”

“…The maximum energy density was 1.7 mJ • cm −2 . The experimental setup and the mechanism of detection of THz radiation with an electrooptical ZnTe crystal were discussed in detail in [13][14][15].…”

Spintronics Based Terahertz Sources

“…In a similar earlier study by Cheng et al [81], a THz amplitude modulation depth of 69% was achieved. The study by Khusyainov et al [82] was more concerned with polarization control via an electric field and the maximum angle of THz polarization rotation by the electric field was observed to be 66 • .…”

Controlled Spintronic Emitter of THz Radiation on an Atomically Thin WS2/Silicon Substrate

“…In the TbCo 2 /FeCo intermetallic heterostructure with uniaxial magnetic anisotropy, a simple method for controlling the polarization of THz radiation by changing only the current through a magnet was demonstrated [16,17]. In a terahertz emitter deposited on a piezoelectric substrate, the possibility of electrically controlling the polarization of THz wave was shown [18,19].…”