Jiří Volný: Electrical transport properties of tetragonal CuMnAs single crystal
Venue: lecture room F2, first floor, Ke Karlovu 5 - Prague 2
We have a pleasure to invite you to attend the joint seminar
of the Department of Condensed Matter Physics (DCMP)
and the Materials Growth and Measurement Laboratory (MGML) http://mgml.eu.
Electrical transport properties of tetragonal CuMnAs single crystal
lecture given by:
Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
The seminar takes place in the lecture room F2
of the Faculty of Mathematics and Physics, Ke Karlovu 5, Praha 2
on Wednesday, 26.2. 2019 from 14:10
On behalf of the DCMP and MGML
Emerging field of antiferromagnetic (AFM) spintronics is drawing a lot of attention due to promising applications in storage devices . One of the promising materials is an AFM metal CuMnAs. Its transport properties have been mostly studied on thin films. So far the main focus has been on spin-orbit torque, allowing for a selective manipulation of magnetic moments in the AFM . This amounts to an effective writing of information. As a method for readout, anisotropic magnetoresistance (AMR) is being used (although little explored), giving different readout signals for two orthogonal orientation of magnetic moments. In this work, we explore resistivity and AMR in a geometry which overcomes the limitations of thin films.
To this end, we have prepared a transport device out of a bulk single crystal grain of tetragonal CuMnAs  using Focused Ion Beam micromachining (FIB). This technique, allowing for precise control over sample geometry, lets us measure resisitivity along arbitrary crystallographic direction. For the first time, we report temperature dependence of both in-plane and out-of-plane resistivity, uncovering large structural transport anisotropy between both principal crystallographic axes. This is further discussed in context of ab initio calculations assuming various types of impurities in our samples.
Regarding the anisotropic magnetoresistance (AMR) which reaches a modest magnitude of 0.12%, we phenomenologically employ the Stoner-Wohlfarth model to identify temperature dependent magnetic anisotropy of our samples and conclude that the field dependence of AMR is more similar to that of antiferromagnets than ferromagnets, suggesting that the origin of AMR is not related to isolated Mn magnetic moments.
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 K. Uhlířová et al., Journal of Alloys and Compounds 771, 680 (2019).
- Wednesday, 26 February 2020 14:10 - 15:10