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Creators/Authors contains: "Dai, Bingqian"

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  1. Abstract

    Achieving spin-pinning at the interface of hetero-bilayer ferromagnet/antiferromagnet structures in conventional exchange bias systems can be challenging due to difficulties in interface control and the weakening of spin-pinning caused by poor interface quality. In this work, we propose an alternative approach to stabilize the exchange interaction at the interface of an uncompensated antiferromagnet by utilizing a gradient of interlayer exchange coupling. We demonstrate this exchange interaction through a designed field training protocol in the odd-layer topological antiferromagnet MnBi2Te4. Our results reveal a remarkable field-trained exchange bias of up to ~ 400 mT, which exhibits high repeatability and can be easily reset by a large training field. Notably, this field-trained exchange bias effect persists even with zero-field initialization, presenting a stark contrast to the traditional field-cooled exchange bias. The highly tunable exchange bias observed in this single antiferromagnet compound, without the need for an additional magnetic layer, provides valuable insight into the exchange interaction mechanism. These findings pave the way for the systematic design of topological antiferromagnetic spintronics.

     
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  2. The electric field manipulates the spin chirality and skyrmion motion direction in a magnetic heterostructure. 
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  4. Abstract

    Topological insulators (TI) and magnetic topological insulators (MTI) can apply highly efficient spin‐orbit torque (SOT) and manipulate the magnetization with their unique topological surface states (TSS) with ultrahigh efficiency. Here, efficient SOT switching of a hard MTI, V‐doped (Bi,Sb)2Te3(VBST), with a large coercive field that can prevent the influence of an external magnetic field, is demonstrated. A giant switched anomalous Hall resistance of 9.2 kΩ is realized, among the largest of all SOT systems, which makes the Hall channel a good readout and eliminates the need to fabricate complicated magnetic tunnel junction (MTJ) structures. The SOT switching current density can be reduced to 2.8 × 10A cm−2, indicating its high efficiency. Moreover, as the Fermi level is moved away from the Dirac point by both gate and composition tuning, VBST exhibits a transition from edge‐state‐mediated to surface‐state‐mediated transport, thus enhancing the SOT effective field to (1.56 ± 0.12) × 10−6 T A−1 cm2and the interfacial charge‐to‐spin conversion efficiency to 3.9 ± 0.3 nm−1. The findings establish VBST as an extraordinary candidate for energy‐efficient magnetic memory devices.

     
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