The authors acknowledge funding by Austrian Science Fund (FWF) project F4509-N16 and W1243-N16. M. Glowacki from the Polish Academy of Science is gratefully acknowledged for providing the LSGM single crystal used in this study. Further, the authors like to thank G. Friedbacher for performing the AFM measurements as well as K. Hradil and W. Artner from the X-ray Center of the Vienna University of Technology for their continuous advice and support.