Ferrimagnetic Tb-Fe based heterostructures: Intriguing properties and applications

CIC nanoGUNE Seminars

Manfred Albrecht, University of Augsburg, Germany
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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Ferrimagnetic Tb-Fe based heterostructures: Intriguing properties and applications Ultrafast magnetization switching is at the heart of both modern information storage technology and fundamental science. In this regard, it was recently observed that ultra-fast magnetization reversal processes can be induced by circularly polarized laser pulses in ferrimagnetic GdFeCo alloy thin films [1]. This novel observation resulted in a broad range of exciting and challenging fundamental questions, and may enable new applications based on ultra-fast spintronics. An overview of our activities on all-optical switching in ferrimagnetic TbFe films [2-4] will be pre-sented. In a further study, we tried to combine this AOS property with magnetic thin films with high magnetic anisotropy such as L10 ordered FePt, which are in high demand for ultra high-density magnetic recording. In this attempt FePt-Tb alloy thin films were investigated. Another intriguing property of ferrimagnetic/ferromagnetic heterostructures is the exchange bias effect. Here, the dependence of the interfacial exchange coupling on the stoichiometry of the fer-rimagnetic TbFe layer was analyzed. A large exchange-bias field up to several Tesla is found to be accompanied by an interfacial domain wall as probed by element specific x-ray magnetic cir-cular dichroism absorption measurements [5]. In addition, unexpected results on the exchange bias effect in two coupled ferrimagnetic TbFe layers will be shown [6]. Recently, a new type of THz emitter has been discovered [7], which is based on the inverse spin Hall effect. These “spintronic” THz emitters can generate a high THz intensity and are broadband up to 30 THz. Here I will show results on the THz emission of a layered spintronic system based on Pt and (TbxFe1−x) alloys for the entire range of Tb content (0 ≤ x ≤ 1) under different external applied magnetic fields [8]. [1] C. D. Stanciu et al., Phys. Rev. Lett. 99, 047601 (2007) [2] A. Hassdenteufel et al., Adv. Mater. 25, 3122 (2013) [3] A. Hassdenteufel et al., Phys. Rev. B 91, 104431 (2015) [4] B. Hebler et al., Frontiers in Materials 3, 8 (2016) [5] C. Schubert et al., Phys. Rev. B 87, 054415 (2013) [6] B. Hebler et al., Phys. Rev. B 95, 104410 (2017) [7] T. Kampfrath et al., Nat. Nanotechnol. 8, 256 (2013) [8] R. Schneider et al., ACS Photonics 5, 3936 (2018) **Host: **A. Berger