Spintronic GdFe/Pt THz emitters

Abstract

We present a spintronic terahertz emitter based on a ferrimagnetic gadolinium-iron alloy (GdxFe1−x) and platinum (Pt). We measure the magnetic-field-dependent terahertz emission of GdxFe1−x/Pt spintronic heterostructures in the entire composition range (0 ≤ x ≤ 1). Excellent agreement is found between the measured data and a theoretical model based on the ratio of in-plane and saturation magnetization, up to a Gd content of x = 0.4 for all applied fields. At a higher Gd content (x ≥ 0.6), the measured terahertz amplitudes and the model deviate, due to the increasing influence of Gd. The GdxFe1−x/Pt emitters share similar properties with TbxFe1−x/Pt emitters, such as a strong increase in terahertz emission for a small rare earth content. However, our systematic study demonstrates that the terahertz emission amplitude of GdxFe1−x/Pt is up to 17 times higher than that of TbxFe1−x/Pt, which is important for the use and further optimization of these spintronic emitters operating at room temperature.

Emerging Spintronics Phenomena and Applications

“…Similar results were reported by Schneider et al for another RE-TM ferrimagnet, Fe1-xTbx[276]. It was found that a CoGd heterostructure emits a stronger THz compared to the CoTb ones possibly due to a large out-ofplane anisotropy in CoTb[277]. The anomalous Hall effect (AHE) as a possible alternate mechanism of THz generation instead of ISHE has been put forward recently[278].…”

Spintronic terahertz emitters: Status and prospects from a materials perspective

“…122 This useful property enables the net magnetization, (M A + M B ), of the ferrimagnet to be effectively tuned by changing the temperature of the material, 122 where a temperature change can be induced by exposure to femtosecond laser pulses. 62,127,128 FIM/NM THz emitters based upon Gd x Fe 1 x alloys have been explored 62,122 as they are archetypal rare-earth transition metal ferrimagnets, exhibiting composition and thickness dependent magnetic properties. 129,130 A recent study by Schneider et al 127 has investigated the composition and magnetic field dependent THz emission from Gd x Fe 1 x (20 nm)/Pt (5 nm) heterostructures over the entire composition range (0  x 1).…”

“…62,127,128 FIM/NM THz emitters based upon Gd x Fe 1 x alloys have been explored 62,122 as they are archetypal rare-earth transition metal ferrimagnets, exhibiting composition and thickness dependent magnetic properties. 129,130 A recent study by Schneider et al 127 has investigated the composition and magnetic field dependent THz emission from Gd x Fe 1 x (20 nm)/Pt (5 nm) heterostructures over the entire composition range (0  x 1). Figure 17 reveals how the THz emission varies with applied magnetic field strength.…”

THz emission from Fe/Pt spintronic emitters with L10-FePt alloyed interface

“…During the last years, THz spintronic emitters have been heavily investigated aiming to obtain large signals and spectral bandwidths and to incorporate them into THz applications ( Papaioannou and Beigang, 2021 ; Bull et al., 2021 ; Wu et al., 2021 ). In particular, a wide range of material properties have been studied including: different material compositions of FM/NM layers with a variety of thicknesses ( Torosyan et al., 2018 ; Seifert et al., 2016 ; Wu et al., 2017 ; Yang et al., 2016 ; Qiu et al., 2018 ), ferrimagnetic/NM structures ( Seifert et al., 2017 ; Schneider et al., 2018 , 2019 ; Fix et al., 2020 ), and antiferromagnetic metal/NM ( Ogasawara et al., 2020 ). In addition, the impact of material interfaces was studied by inserting non-magnetic interlayer material such as Cu,Al, Ti, Au, and ZnO layers in FM/X/NM trilayers ( Gueckstock et al., 2021 ; Papaioannou et al., 2018 ; Seifert et al., 2018 ; Hawecker et al., 2021 ; Li et al., 2018 ).…”