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1. Evidence of cluster dipole states in germanium detectors operating at temperatures below 10 K

   https://doi.org/10.1063/5.0094194  

   Mei, D-M; Panth, R.; Kooi, K.; Mei, H.; Bhattarai, S.; Raut, M.; Acharya, P.; Wang, G-J (June 2022, AIP Advances)

   By studying charge trapping in germanium detectors operating at temperatures below 10 K, we demonstrate for the first time that the formation of cluster dipole states from residual impurities is responsible for charge trapping. Two planar detectors with different impurity levels and types are used in this study. When drifting the localized charge carriers created by α particles from the top surface across a detector at a lower bias voltage, significant charge trapping is observed when compared to operating at a higher bias voltage. The amount of charge trapping shows a strong dependence on the type of charge carriers. Electrons are trapped more than holes in a p-type detector, while holes are trapped more than electrons in an n-type detector. When both electrons and holes are drifted simultaneously using the widespread charge carriers created by γ rays inside the detector, the amount of charge trapping shows no dependence on the polarity of bias voltage. 

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2. Charge distribution guided by grain crystallographic orientations in polycrystalline battery materials

   https://doi.org/10.1038/s41467-019-13884-x  

   Xu, Zhengrui; Jiang, Zhisen; Kuai, Chunguang; Xu, Rong; Qin, Changdong; Zhang, Yan; Rahman, Muhammad Mominur; Wei, Chenxi; Nordlund, Dennis; Sun, Cheng-Jun; et al (January 2020, Nature Communications)

   Abstract Architecting grain crystallographic orientation can modulate charge distribution and chemomechanical properties for enhancing the performance of polycrystalline battery materials. However, probing the interplay between charge distribution, grain crystallographic orientation, and performance remains a daunting challenge. Herein, we elucidate the spatially resolved charge distribution in lithium layered oxides with different grain crystallographic arrangements and establish a model to quantify their charge distributions. While the holistic “surface-to-bulk” charge distribution prevails in polycrystalline particles, the crystallographic orientation-guided redox reaction governs the charge distribution in the local charged nanodomains. Compared to the randomly oriented grains, the radially aligned grains exhibit a lower cell polarization and higher capacity retention upon battery cycling. The radially aligned grains create less tortuous lithium ion pathways, thus improving the charge homogeneity as statistically quantified from over 20 million nanodomains in polycrystalline particles. This study provides an improved understanding of the charge distribution and chemomechanical properties of polycrystalline battery materials. 

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3. Investigating charge transport in a p -Si/ n -poly(benzimidazobenzophenanthroline)-BBL thin film heterojunction diode

   https://doi.org/10.1088/1361-648X/adcdb0  

   Cruz-Arzon, Alejandro J; Pinto, Nicholas J (April 2025, Journal of Physics: Condensed Matter)

   Abstract The physics of charge transport across the interface in an inorganic Si/organic conducting polymer junction diode has received little attention compared to the inorganicp–nsilicon diode. One reason is the amorphous nature of the organic polymer and the polymer chain orientation which introduces disorder and barriers to charge flow. Herein we first present an easy technique to fabricate an inorganic/organic,p-Si/n-poly(benzimidazobenzophenanthroline-BBL) junction diode. The physics of charge transport across the heterojunction, and in the BBL film is then analyzed from the device current-voltage characteristics as a function of temperature in the range 150 K <T< 370 K. The temperature dependence of the diode ideality parameter and of the saturation current density demonstrate that tunneling enhanced charge recombination via exponential trap distributions in the depletion region was responsible for charge transport across the junction. Furthermore, the temperature dependence of the diode conductance revealed that thermal activation and hopping both contributed to charge transport in the BBL film away from the junction. BBL is a ladder polymer with a discrete layered crystal structure that is oriented perpendicular to the substrate. Such polymer chain orientation, combined with a distribution of bond lengths and numerous conjugation paths available for charge delocalization result in the multiple charge transport mechanisms as observed in the diode. 

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4. Incommensurate charge-stripe correlations in the kagome superconductor CsV3Sb5−xSnx

   https://doi.org/10.1038/s41535-023-00570-x  

   Kautzsch, Linus; Oey, Yuzki M.; Li, Hong; Ren, Zheng; Ortiz, Brenden R.; Pokharel, Ganesh; Seshadri, Ram; Ruff, Jacob; Kongruengkit, Terawit; Harter, John W.; et al (July 2023, npj Quantum Materials)

   Abstract The class ofAV₃Sb₅(A=K, Rb, Cs) kagome metals hosts unconventional charge density wave states seemingly intertwined with their low temperature superconducting phases. The nature of the coupling between these two states and the potential presence of nearby, competing charge instabilities however remain open questions. This phenomenology is strikingly highlighted by the formation of two ‘domes’ in the superconducting transition temperature upon hole-doping CsV₃Sb₅. Here we track the evolution of charge correlations upon the suppression of long-range charge density wave order in the first dome and into the second of the hole-doped kagome superconductor CsV₃Sb_5−xSn_x. Initially, hole-doping drives interlayer charge correlations to become short-ranged with their periodicity diminished along the interlayer direction. Beyond the peak of the first superconducting dome, the parent charge density wave state vanishes and incommensurate, quasi-1D charge correlations are stabilized in its place. These competing, unidirectional charge correlations demonstrate an inherent electronic rotational symmetry breaking in CsV₃Sb₅, and reveal a complex landscape of charge correlations within its electronic phase diagram. Our data suggest an inherent 2k_fcharge instability and competing charge orders in theAV₃Sb₅class of kagome superconductors. 

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5. High spatial resolution charge sensing of quantum Hall states

   https://doi.org/10.1073/pnas.2424781122  

   Chiu, Cheng-Li; Wang, Taige; Fan, Ruihua; Watanabe, Kenji; Taniguchi, Takashi; Liu, Xiaomeng; Zaletel, Michael P; Yazdani, Ali (February 2025, Proceedings of the National Academy of Sciences)

   Charge distribution offers a unique fingerprint of important properties of electronic systems, including dielectric response, charge ordering, and charge fractionalization. We develop an architecture for charge sensing in two-dimensional electronic systems in a strong magnetic field. We probe local change of the chemical potential in a proximitized detector layer using scanning tunneling microscopy, allowing us to infer the chemical potential and the charge profile in the sample. Our technique has both high energy (<0.3 meV) and spatial (<10 nm) resolution exceeding that of previous studies by an order of magnitude. We apply our technique to study the chemical potential of quantum Hall liquids in monolayer graphene under high magnetic fields and their responses to charge impurities. The chemical potential measurement provides a local probe of the thermodynamic gap of quantum Hall ferromagnets and fractional quantum Hall states. The screening charge profile reveals spatially oscillatory response of the quantum Hall liquids to charge impurities and is consistent with the composite Fermi liquid picture close to the half-filling. Our technique also paves the way to map moiré potentials, probe Wigner crystals, and investigate fractional charges in quantum Hall and Chern insulators. 

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