Publications by authors named "Sheng-Zhu Ho"

In semiconducting monolayer transition metal dichalcogenides (ML-TMDs), broken inversion symmetry and strong spin-orbit coupling result in spin-valley lock-in effects so that the valley degeneracy may be lifted by external magnetic fields, potentially leading to real-space structural transformation. Here, magnetic field (B)-induced giant electric hysteretic responses to back-gate voltages are reported in ML-MoS field-effect transistors (FETs) on SiO/Si at temperatures < 20 K. The observed hysteresis increases with |B| up to 12 T and is tunable by varying the temperature.

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  • This study investigates how ferroelectric catalysts can change their catalytic activities by switching electric polarizations, using layered bismuth oxyselenide (L-BiOSe) microreactors.
  • It introduces a new method called selective-area ionic liquid gating to control the direction of dipole orientation in L-BiOSe, leading to variations in catalytic reactions, with upward polarization favoring oxygen evolution and downward polarization favoring hydrogen evolution.
  • The research demonstrates that by integrating L-BiOSe microreactors with different polarizations, it is possible to achieve overall water splitting, highlighting the potential for designing catalysts that can switch surface polarizations.
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  • Recent research highlights the use of electronic polarizations, like ferroelectric and spin polarizations, to improve the efficiency of photocatalytic reactions, specifically for reducing carbon dioxide (CO).
  • The study focuses on a 2D layered crystal called copper indium thiophosphate (CuInPS), showing that controlling ferroelectric polarization through phase transitions and electrical poling significantly enhances CO reduction efficiency.
  • The research also investigates the role of spin electrons by introducing sulfur vacancies and applying a magnetic field to further boost CO reduction performance, utilizing advanced characterization techniques to understand these enhancements.
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Understanding the magnetic and ferroelectric ordering of magnetoelectric multiferroic materials at the nanoscale necessitates a versatile imaging method with high spatial resolution. Here, soft X-ray ptychography is employed to simultaneously image the ferroelectric and antiferromagnetic domains in an 80 nm thin freestanding film of the room-temperature multiferroic BiFeO (BFO). The antiferromagnetic spin cycloid of period 64 nm is resolved by reconstructing the corresponding resonant elastic X-ray scattering in real space and visualized together with mosaic-like ferroelectric domains in a linear dichroic contrast image at the Fe L edge.

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Efficient and durable electrocatalysts with superior activity are needed for the production of green hydrogen with a high yield and low energy consumption. Electrocatalysts based on transition metal oxides hold dominance due to their abundant natural resources, regulable physical properties, and good adaptation to a solution. In numerous oxide catalyst materials, ferroelectrics, possessing semiconducting characteristics and switchable spontaneous polarization, have been considered promising photoelectrodes for solar water splitting.

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Strain engineering has quickly emerged as a viable option to modify the electronic, optical, and magnetic properties of 2D materials. However, it remains challenging to arbitrarily control the strain. Here we show that, by creating atomically flat surface nanostructures in hexagonal boron nitride, we achieve an arbitrary on-chip control of both the strain distribution and magnitude on high-quality molybdenum disulfide.

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Strontium titanate (STO), with a wide spectrum of emergent properties such as ferroelectricity and superconductivity, has received significant attention in the community of strongly correlated materials. In the strain-free STO film grown on the SrRuO buffer layer, the existing polar nanoregions can facilitate room-temperature ferroelectricity when the STO film thickness approaches 10 nm. Here we show that around this thickness scale, the freestanding STO films without the influence of a substrate show the tetragonal structure at room temperature, contrasting with the cubic structure seen in bulk form.

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Multiferroics-materials that exhibit coupled ferroic orders-are considered to be one of the most promising candidate material systems for next-generation spintronics, memory, low-power nanoelectronics and so on. To advance potential applications, approaches that lead to persistent and extremely fast functional property changes are in demand. Herein, it is revealed that the phase transition and the correlated ferroic orders in multiferroic BiFeO (BFO) can be modulated via illumination of single short/ultrashort light pulses.

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With the rise of Internet of Things, the presence of flexible devices has attracted significant attention owing to design flexibility. A ferroelectric field-effect transistor (FeFET), showing the advantages of high speed, nondestructive readout, and low-power consumption, plays a key role in next-generation technology. However, the performance of these devices is restricted since conventional flexible substrates show poor thermal stability to integrate traditional ferroelectric materials, limiting the compatibility of wearable devices.

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