[19p-E215-1~17] 4.5 Terahertz Photonics

▲ [19p-E215-5] Spintronic Terahertz Generation Using an Optimized Metallic Bilayer of Epitaxial Grown Fe/Pt on Silicon Substrate

〇(PC)Valynn Katrine Magusara¹、Garik Torosyan²、Miezel Talara¹、Jessica Afalla¹、Laura Scheuer³、Dominik Sokoluk³、Evangelos Th. Papaioannou³、Marco Rahm³、Rene Beigang³、Masahiko Tani¹ (1.FIR Center, Univ. of Fukui、2.Photonic Center Kaiserslautern、3.OPTIMAS, Technische Univ. of Kaiserslautern)

キーワード：THz spintronics, THz generation, spintronic emitter

Metallic spintronic heterostructures with ferromagnetic and non-ferromagnetic films emit THz radiation via a distinct THz generation mechanism, which involves the conversion of spin currents into transverse charge currents. We have previously demonstrated that an optimized bilayer of 2-nm Fe and 3-nm Pt on 500-µm MgO substrate is a remarkably versatile spintronic THz emitter, as it exhibits fairly the same THz emission efficiency at 780-nm and 1550-nm pulsed excitation wavelengths. In this work, we studied spintronic THz generation when the Fe/Pt bilayer is epitaxial grown on 500-µm Si substrate. Unlike the Fe/Pt on MgO, the Fe/Pt on Si is less efficient to use with 780-nm optical pump, which has sufficient photon energy to generate free charge carriers in the Si substrate. Such carriers absorb THz radiation, resulting in THz losses and significantly reduced measured THz emission. The Fe/Pt on Si is demonstrated as an efficient alternative THz emitter particularly for systems that are driven by fs fiber lasers with 1550-nm output wavelength.