Chiral magnets give rise to the anti-symmetric Dzyaloshinskii-Moriya (DM) interaction, which induces topological nontrivial textures such as magnetic skyrmions. The topology is characterized by integer values of the topological charge. In this work, we performed the Monte-Carlo calculation of a two-dimensional model of the chiral magnet. A surprising upturn of the topological charge is identified at high fields and high temperatures. This upturn is closely related to thermal fluctuations at the atomic scale, and is explained by a simple physical picture based on triangulation of the lattice. This emergent topology is also explained by a field-theoretic analysis using CP 1 formalism.

Measurements of the temperature-dependent resistivity of high-mobility GaAs/GaAlAs heterojunctions are used to measure the effective mass of Composite Fermions (CF). The CF effective mass is found to increase approximately linearly with the effective field B * up to effective fields of 14 T. Data from all fractions around ν = 1/2 are unified by the single parameter B * for samples studied over a wide range of temperature. The energy gap is found to increase as √ B * at high fields. Hydrostatic pressure is used to reduce the value of the electron g-factor, and this is shown to have a large effect on the relative strengths of different fractions. By 13.4 kbar, where the Zeeman energy is only 1/4 of its value at 0 bar, fractions with odd numerators are found to be strongly suppressed, and new features with even numerators appear. The energy gaps measured for 5/3 as a function of carrier density and pressure are consistent with a g-factor equal to the bulk value enhanced by a factor of two due to exchange interactions.

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We have performed 4 K magnetotransport measurements on almost intrinsic InAs/GaSb multi quantum wells under hydrostatic pressure. Through careful configuration of the growth we are able to produce samples that have differing interface monolayers (either InSb or GaAs). Analysing the data to obtain the overlap we find that InSb interface samples have an overlap 30 ± 10 meV larger than GaAs in good agreement with recent theoretical predictions.