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MA: Fachverband Magnetismus
MA 61: Caloric Effects
MA 61.14: Vortrag
Freitag, 20. März 2020, 12:45–13:00, HSZ 101
Experimental determination of the thermal conductivity of oxide barriers in magnetic tunnel junctions — Hyejin Jang1, Luca Marnitz2, Torsten Huebner2, Johannes Kimling1, Ulrike Martens3, Jakob Walowski3, Markus Münzenberg3, Andy Thomas4, Günter Reiss2, David Cahill1 und •Timo Kuschel2 — 1University of Illinois, Urbana, USA — 2Bielefeld University, Germany — 3Greifswald University, Germany — 4IFW, Dresden, Germany
The tunnel magneto-Seebeck (TMS) effect in magnetic tunnel junctions (MTJs) has large potential for future nanoelectronic devices [1]. However, quantitative determination of the TMS coefficients requires knowledge of the temperature drop across the tunnel barrier and, thus, of the thermal conductivity of the oxide barrier material. Here, we present two new approaches to obtain the barrier’s thermal conductivity, which is usually difficult to access experimentally. For the first approach, we utilize laser-induced TMS in combination with finite-element modeling extracting values of the thermal conductivity of 0.7 W/(K·m) for MgAl2O4 and 5.8 W/(K·m) for MgO [2]. The second method uses ultrafast thermoreflectance and magnetooptic Kerr effect thermometry and provides values of the thermal conductivity of 0.4-0.6 W/(K·m) for both oxide barrier materials [3]. These results are in nice agreement with theoretical predictions for ultra-thin oxide barriers [4].
[1] Kuschel et al., J. Phys. D: Appl. Phys. 52, 133001 (2019)
[2] Huebner et al., J. Phys. D: Appl. Phys. 51, 224006 (2018)
[3] Jang, Marnitz, Huebner, Kimling, Kuschel, Cahill, under review
[4] Zhang et al., Phys. Rev. Lett. 115, 037203 (2015)