Accepted articles

Instruments and methods of investigation


Scaling of the anomalous Hall effect as a method for determining the percolation threshold and metal-insulator transition in magnetic nanocomposites with intergranular interaction

 a,  b,  b, c,  a,  a, d,  a,  a, e,  f,  f,  f,  f, g,  a, g, h
a National Research Centre ‘Kurchatov Institute’, pl. akad. Kurchatova 1, Moscow, 123182, Russian Federation
b Kapitza Institute of Physical Problems, Russian Academy of Sciences, ul. Kosygina 2, Moscow, 117334, Russian Federation
c HSE University, ul. Myasnitskaya 20, Moscow, 101000, Russian Federation
d Voronezh State Technical University, Moskovskii prosp. 14, Voronezh, 394026, Russian Federation
e Moscow Institute of Physics and Technology (National Research University), Institutskii per. 9, Dolgoprudny, Moscow Region, 141701, Russian Federation
f Lomonosov Moscow State University, Faculty of Physics, Leninskie Gory 1 build. 2, Moscow, 119991, Russian Federation
g Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, ul. Izhorskaya 13/19, Moscow, 127412, Russian Federation
h Kotelnikov Institute of Radioengineering and Electronics of the Russian Academy of Sciences, ul. Mokhovaya 11, kor. 7, Moscow, 125009, Russian Federation

Using the example of nanocomposite (NC) films (CoFeB)x(LiNbO3)100-x, in which, at relatively high temperatures T ≿ 10 K, a "weakly insulating" regime in the temperature dependence of the conductivity logarithmic type σ ∝ lnT is observed, characteristic of a strong tunneling bond between granules, scaling in the behavior of the resistance of the anomalous Hall effect (AHE) resistance ρAHE from the longitudinal resistance R is studied in detail. The studies were performed in fields up to 14 T at temperatures T = 0.4-200 K in the range of metal phase content x ≈ 35-60 at.%, covering the percolation transition. It was found that the degree n in the scaling dependence ρAHE ∝ [ρ(T)]n behaves non-monotonically: in the ranges x ≈ 35-44 at.% and x ≈ 50-60 at.% there is a clear increase in the indicator, and in the range x ≈ 44-50 at.% the value of n practically does not change. We consider that the kink regions in the n(x) dependence indicate a change in the NC conductivity mechanism and determine the percolation threshold (at xp ≈ 50 at.%) and the metal-insulator transition (xc ≈ 44 at.%), which do not match up in these systems. The results of the analysis of the behavior of σ(T) at subhelium T = 0.4-3 K confirm this conclusion. The study of the magnetic properties of NC with changes in the content of the metallic phase by ferromagnetic resonance and magneto-optical spectroscopy also indicates the presence of features in the vicinity of concentrations x ≈ 44 and 50 at.%.

Keywords: anomalous Hall effect, nanocomposites, metal-insulator transition, percolation threshold
DOI: 10.3367/UFNe.2024.11.039814
Citation: Nikolaev S N, Drovosekov A B, Dmitrieva M Yu, Chernoglazov K Yu, Sitnikov A V, Taldenkov A N, Vasiliev A L, Gan’shina E A, Pripechenkov I M, Simdyanova M A, Granovskii A B, Rylkov V V "Scaling of the anomalous Hall effect as a method for determining the percolation threshold and metal-insulator transition in magnetic nanocomposites with intergranular interaction" Phys. Usp., accepted

Received: 14th, August 2024, 23rd, November 2024

Оригинал: Николаев С Н, Дровосеков А Б, Дмитриева М Ю, Черноглазов К Ю, Ситников А В, Талденков А Н, Васильев А Л, Ганьшина Е А, Припеченков И М, Симдянова М А, Грановский А Б, Рыльков В В «Cкейлинг аномального эффекта Холла как метод определения порога перколяции и перехода металл-изолятор в магнитных нанокомпозитах с межгранульным взаимодействием» УФН, принята к публикации; DOI: 10.3367/UFNr.2024.11.039814

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