Pump-probe magneto-optical studies of thin-film ferromagnets and antiferromagnets Текст научной статьи по специальности «Физика»

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Pump-probe magneto-optical studies of thin-film ferromagnets and antiferromagnets

P. Nemec1

1Charles University, Faculty of Mathematics and Physics, Prague 2, Czech Republic

Recent breakthroughs in electrical detection and manipulation of antiferromagnets have opened a new avenue in the research of non-volatile spintronic devices. Antiparallel spin sublattices in antiferromagnets lead to the insensitivity to magnetic field perturbations, multi-level stability and ultra-fast spin dynamics. However, these features also make the characterization of antiferromagnetic materials, in particular of thin metallic films suitable for spintronics, a major challenge [1]. In this contribution we show how the know-how, which we achieved in the pumpprobe study of diluted ferromagnetic semiconductor (Ga,Mn)As [2,3], can be transferred to the research of thin films of compensated antiferromagnetic metal CuMnAs [4], where terahertz writing speed in a non-volatile antiferromagnetic memory device has been demonstrated recently [5].

Fig. 1. Investigation of 10 nm thick film of compensated antiferromagnetic metal CuMnAs [4]. a) Schematic illustration showing how strong laser pulse-induced demagnetization leads to a reduction of Voigt effect-related probe polarization rotation, which is detected as a function of time delay Dt between pump and probe pulses for various probe pulses polarization plane orientations e, as shown in b). c) Probe-polarization dependence of pump-induced change of MO signal measured for Dt = 60 ps at 15 K and 300 K, the vertical arrow depicts the position of the sample easy axis. d) Determination of the Neel temperature, depicted by a vertical arrow, from temperature dependence of MO signal (black). The red line is a temperature derivative of the sample resistivity.

References

[1] P. Nemec, M. Fiebig, T. Kampfrath, and A. V. Kimel, Antiferromagnetic opto-spintronics, Nature Physics 14, 229 (2018).

[2] P. Nemec et al., Experimental observation of the optical spin transfer torque, Nature Physics 8, 411 (2012).

[3] N. Tesarovâ, P. Nemec et al., Experimental observation of the optical spin-orbit torque, Nature Photonics 7, 492 (2013).

[4] V. Saidl, P. Nemec et al., Optical determination of the Neel vector in a CuMnAs thin-film antiferromagnet, Nature Photonics 11, 91 (2017) .

[5] K. Olejnik, et al, Terahertz electrical writing speed in an antiferromagnetic memory. Science Advances 4, eaar3566 (2018).