2017/05/31 by Martin Lonsky, Jan Teschabai-Oglu, K. Pierz +9
Chemistry · Materials Science · Physics and Astronomy · #Analytical Chemistry (journal) #Artificial intelligence #Chemistry #Computer science #Condensed matter physics #Context (archaeology) #Curie temperature #Ferromagnetism #Impurity #Magnetic and transport properties of perovskites and related materials #Magnetic field #Magnetic semiconductor #Magnetization #Materials science #Noise (video) #Phase (matter) #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #ZnO doping and properties #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.97.054413
published as Phys. Rev. B 97, 054413 (2018)
arxiv created 2017/11/17 · openalex created_date 2017/12/04 · openalex publication_date 2018/02/13 · arxiv updated 2018/02/21 · openalex updated_date 2026/08/05
We present systematic temperature-dependent resistance noise measurements on a series of ferromagnetic Ga_1\ensuremath-xMnxAs epitaxial thin films covering a large parameter space in terms of the Mn content x and other variations regarding sample fabrication. We infer that the electronic noise is dominated by switching processes related to impurities in the entire temperature range. While metallic compounds with x>2% do not exhibit any significant change in the low-frequency resistance noise around the Curie temperature TC, we find indications for an electronic phase separation in films with x<2% in the vicinity of TC, manifesting itself in a maximum in the noise power spectral density. These results are compared with noise measurements on an insulating Ga_1\ensuremath-xMnxP reference sample, for which the evidence for an electronic phase separation is even stronger and a possible percolation of bound magnetic polarons is discussed. Another aspect addressed in this work is the effect of ion-irradiation-induced disorder on the electronic properties of Ga_1\ensuremath-xMnxAs films and, in particular, whether any electronic inhomogeneities can be observed in this case. Finally, we put our findings into the context of the ongoing debate on the electronic structure and the development of spontaneous magnetization in these materials.