arXiv subjects

Maurice E. Bal

Publications and source records attributed to Maurice E. Bal.

3 recordsLinked to original sources

arXiv2026

Revealing quantum metric multipoles in magnetic topological insulator MnBi2Te4

Nonlinear electronic transport has emerged as a powerful probe of the quantum geometry in topological quantum materials, where the band topology and broken symmetries facilitate power law current voltage responses beyond Ohms law. While nonlinear transport of the second and third orders has been studied in several quantum materials, higher-order transport has so far mainly remained experimentally inaccessible, leaving more detailed features of the quantum geometry unexplored. Here, we observe higher order nonlinear electronic transport up to the seventh harmonic order in multilayer magnetic topological insulator MnBi2Te4. We find an even-odd behavior where the odd order nonlinear transport components dominate while the even-order ones are suppressed. Temperature and magnetic field dependent measurements show a strong correlation between the nonlinear transport and the magnetic phases of MnBi2Te4. Through scaling analysis and theoretical calculations, quantum metric multipoles and nonlinear Drude conductivities are identified as the microscopic origins of the nonlinear transport.

cond-mat.mes-hall↗

arXiv2022

Disentangling electrical switching of antiferromagnetic NiO using high magnetic fields

Recent demonstrations of the electrical switching of antiferromagnets (AFs) have given an enormous impulse to the field of AF spintronics. Many of these observations are plagued by non-magnetic effects that are very difficult to distinguish from the actual magnetic ones. Here, we study the electrical switching of thin (5 nm) NiO films in Pt/NiO devices using magnetic fields up to 15 T to quantitatively disentangle these magnetic and non-magnetic effects. We demonstrate that these fields suppress the magnetic components of the electrical switching of NiO, but leave the non-magnetic components intact. Using a monodomainization model the contributions are separated, showing how they behave as a function of the current density. These results show that combining electrical methods and strong magnetic fields can be an invaluable tool for AF spintronics, allowing for implementing and studying electrical switching of AFs in more complex systems.

cond-mat.mes-hall↗

arXiv2021

High-quality Two-Dimensional Electron Gas in Undoped InSb Quantum Wells

We report on transport experiments through high-mobility gate-tunable undoped InSb QWs. Due to the elimination of any Si modulation doping, the gate-defined two-dimensional electron gases in the quantum wells display a significantly increased mobility of 260,000 cm$^2$/Vs at a rather low density of $2.4\times10^{11}$ cm$^{-2}$. Using magneto-transport experiments, we characterize spin-orbit interactions by measuring weak antilocalization. Furthermore, by measuring Shubnikov-de Haas oscillations in tilted magnetic fields, we find that the g-factor agrees with $k \cdot p$ theory calculations at low magnetic fields but grows with spin polarization and carrier density at high magnetic fields. Additionally, signatures of Ising quantum Hall ferromagnetism are found at filling factor $ν$ = 2 for tilt angles where the Landau level energy equals the Zeeman energy. Despite the high mobility, the undoped InSb quantum wells exhibit no fractional quantum Hall effect up to magnetic fields of 25 T.

cond-mat.mes-hall↗