Multiferroic hexagonal RMnO(3) (R=rare earths) crystals exhibit dense networks of vortex lines at which six domain walls merge. While the domain walls can be readily moved with an applied electric field, the vortex cores so far have been impossible to control. Our experiments demonstrate that shear strain induces a Magnus-type force pulling vortices and antivortices in opposite directions and unfolding them into a topological stripe domain state. We discuss the analogy between this effect and the current-driven dynamics of vortices in superconductors and superfluids.

ABSTRACT:The recent emergence of topological insulators (TI) has spurred intensive efforts to grow TI thin films on various substrates. However, little is known about how robust the topological surface states (TSS) are against disorders and other detrimental effects originating from the substrates.Here, we report observation of a well-defined TSS on Bi 2 Se 3 films grown on amorphous SiO 2 (aSiO 2 ) substrates and a large gating effect on these films using the underneath doped-Si substrate as the back gate. The films on a-SiO 2 were composed of c-axis ordered but random

Quantum anomalous Hall effect (QAHE) can only be realized at extremely low temperatures in magnetically doped topological insulators (TIs) due to limitations inherent with the doping process. In an effort to boost the quantization temperature of QAHE, magnetic proximity effect in magnetic insulator/TI heterostructures has been extensively investigated. However, the observed anomalous Hall resistance has never been more than several Ohms, presumably owing to the interfacial disorders caused by the structural and chemical mismatch. Here, we show that, by growing (BixSb1−x)2Te3 (BST) thin films on structurally and chemically well-matched, ferromagnetic-insulating CrGeTe3 (CGT) substrates, the proximity-induced anomalous Hall resistance can be enhanced by more than an order of magnitude. This sheds light on the importance of structural and chemical match for magnetic insulator/TI proximity systems.Keywords: magnetic proximity effect, anomalous Hall effect, CrGeTe3, (BixSb1−x)2Te3 , magnetic topological insulator

Seemingly symmetric nanoscale cylinders have hidden asymmetry of charge distribution.

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