The basic condition for conduction relevant research is the availability of suitable samples. Despite the many crystal growth techniques available in MGML, including solution growth, modified Czochralski, floating zone or Bridgman method, several growth difficulties can always remain unsolved leading to very small or multiphase samples. We have implemented a microstructuring technique [1] of multiphase or irregular samples to create devices for charge transport measurements (see Figure 1 and 2).

This technique allows us fabrication of samples with well-defined crystal orientation and dimensions so the resistivity can be determined with high precision despite sample size.

In our recent paper [2], we studied charge transport properties of a bulk tetragonal CuMnAs single crystal. CuMnAs is a room temperature antiferromagnet with promising applications in spintronics [3]. Using FIB, we were able to isolate oriented lamella out of a small single crystalline grain and measure (for the first time) both its resistivity along principal crystallographic axes (Figure 3) and magnetotransport properties, including anisotropic magnetoresistance (AMR), for comparison with calculations.

Fig. 1: Two lamellas fabricated by FIB are connected to the original crystal by a tiny bridge (left, detail in the right).

Fig. 2: They are transferred onto a substrate with prefabricated leads (left) using a capton needle (inset), electrical connection between the lamella and the leads is made using GIS Pt deposition (right).

Fig. 3: Resistivity of bulk CuMnAs measured along a- (ρ_xx) and c-axes (ρ__zz) shown by solid lines.

[1] P.J.W. Moll, Focused Ion Beam Microstructuring of Quantum Matter, (2018) 147–164.
[2] J. Volný, D. Wagenknecht, J. Železný, P. Harcuba, E.D. Nedellec, R.H. Colman, J. Kudrnovský, I. Turek, K. Uhlířová, Electrical transport properties of bulk tetragonal CuMnAs Phys. Rev. Mat. 4 (2020) 064403.
[3] K. Olejník, V. Schuler, X. Marti, V. Novák, Z. Kašpar, P. Wadley, R.P. Campion, K.W. Edmonds, B.L. Gallagher, J. Garces, M. Baumgartner, P. Gambardella, T. Jungwirth, Antiferromagnetic CuMnAs multi-level memory cell with microelectronic compatibility, Nat. Commun. 8 (2017) 15434.

Share This Post :

paperresisitivityFIB