100 research outputs found
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Role of topology in compensated magnetic systems
Topology plays a crucial and multifaceted role in solid state physics, leading to a remarkable array of newly investigated materials and phenomena. In this Perspective, we provide a brief summary of well-established model materials with a particular focus on compensated magnets and highlight key phenomena that emerge due to the influence of topology in these systems. The overview covers various magneto-transport phenomena, with a particular focus on the extensively investigated anomalous magneto-transport effects. Furthermore, we look into the significance of topology in understanding elementary magnetic excitations, namely magnons, where the role of topology gained considerable attention from both theoretical and experimental perspectives. Since electrons and magnons carry energy, we explore the implications of topology in combined heat and spin transport experiments in compensated magnetic systems. At the end of each section, we highlight intriguing unanswered questions in this research direction. To finally conclude, we offer our perspective on what could be the next advancements regarding the interaction between compensated magnetism and topology
Topological Hall effect in thin films of MnPtSn
Spin chirality in metallic materials with non-coplanar magnetic order can
give rise to a Berry phase induced topological Hall effect. Here, we report the
observation of a large topological Hall effect in high-quality films of
MnPtSn that were grown by means of magnetron sputtering on MgO(001).
The topological Hall resistivity is present up to T below
the spin reorientation transition temperature, ~K. We find, that the
maximum topological Hall resistivity is of comparable magnitude as the
anomalous Hall resistivity. Owing to the size, the topological Hall effect is
directly evident prior to the customarily performed subtraction of magnetometry
data. Further, we underline the robustness of the topological Hall effect in
Mn\textsubscript{2-x}PtSn by extracting the effect for multiple stoichiometries
(x~=~0.5, 0.25, 0.1) and film thicknesses (t = 104, 52, 35~nm) with maximum
topological Hall resistivities between cm and
cm at 150~K.Comment: 6 pages, 5 figure
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Probing magnetic properties at the nanoscale: in-situ Hall measurements in a TEM
We report on advanced in-situ magneto-transport measurements in a transmission electron microscope. The approach allows for concurrent magnetic imaging and high resolution structural and chemical characterization of the same sample. Proof-of-principle in-situ Hall measurements on presumably undemanding nickel thin films supported by micromagnetic simulations reveal that in samples with non-trivial structures and/or compositions, detailed knowledge of the latter is indispensable for a thorough understanding and reliable interpretation of the magneto-transport data. The proposed in-situ approach is thus expected to contribute to a better understanding of the Hall signatures in more complex magnetic textures
Thickness dependence of the anomalous Hall effect in thin films of the topological semimetal CoMnGa
Topological magnetic semimetals promise large Berry curvature through the
distribution of the topological Weyl nodes or nodal lines and further novel
physics with exotic transport phenomena. We present a systematic study of the
structural and magnetotransport properties of CoMnGa films from thin (20
nm) to bulk like behavior (80 nm), in order to understand the underlying
mechanisms and the role on the topology. The magnetron sputtered CoMnGa
films are -ordered showing very good heteroepitaxy and a
strain-induced tetragonal distortion. The anomalous Hall conductivity was found
to be maximum at a value of 1138 S/cm, with a corresponding anomalous Hall
angle of 13 %, which is comparatively larger than topologically trivial metals.
There is a good agreement between the theoretical calculations and the Hall
conductivity observed for the 80 nm film, which suggest that the effect is
intrinsic. Thus, the CoMnGa compound manifests as a promising material
towards topologically-driven spintronic applications.Comment: 7 pages, 5 figures, 1 tabl
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Topological Hall effect in thin films of Mn1.5PtSn
Spin chirality in metallic materials with noncoplanar magnetic order can give rise to a Berry phase induced topological Hall effect. Here, we report the observation of a large topological Hall effect in high-quality films of Mn1.5PtSn that were grown by means of magnetron sputtering on MgO(001). The topological Hall resistivity is present up to μ0H≈4T below the spin reorientation transition temperature, Ts=185 K. We find that the maximum topological Hall resistivity is of comparable magnitude as the anomalous Hall resistivity. Owing to the size, the topological Hall effect is directly evident prior to the customarily performed subtraction of magnetometry data. Further, we underline the robustness of the topological Hall effect in Mn2-xPtSn by extracting the effect for multiple stoichiometries (x=0.5,0.25,0.1) and film thicknesses (t=104,52,35 nm) with maximum topological Hall resistivities between 0.76 and 1.55μΩcm at 150 K. © 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI
Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction
Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the [] direction in the vicinity of the wurtzite Bragg peak. The maxima of the Patterson function encode both the distances between the fault planes and the type of the fault planes with the sensitivity of a single atomic bilayer. The positions of the fault planes are deduced from the positions and shapes of the maxima of the Patterson function and they are in excellent agreement with the positions found with transmission electron microscopy of the same nanowire
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