We derive and investigate numerically a minimal yet detailed spin-polaron model that describes lightly doped CuO2 layers. The low-energy physics of a hole is studied by total-spin-resolved exact diagonalization on clusters of up to 32 CuO2 unit cells, revealing features missed by previous studies. In particular, spin-polaron states with total spin 3/2 are the lowest eigenstates in some regions of the Brillouin zone. In these regions, and also at other points, the quasiparticle weight is identically zero indicating orthogonal states to those represented in the one electron Green's function. This highlights the importance of the proper treatment of spin fluctuations in the many-body background.
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http://dx.doi.org/10.1103/PhysRevLett.106.036401 | DOI Listing |
ACS Omega
December 2024
Institute of Photoelectronic Thin Film Devices and Technology, Nankai University, Tianjin 300350, China.
Silicon heterojunction (SHJ) solar cells, as one of the most promising passivated contact solar cell technologies of the next generation, have the advantages of high conversion efficiency, high open-circuit voltage, low-temperature coefficient, and no potential-induced degradation. For the single-side rear-emitter SHJ solar cells, the n-type carrier selective layer, which serves as the light-incident side, plays a pivotal role in determining the performance of heterojunction devices. Consequently, a superior n-doped layer should exhibit high optical transmittance and minimal optical absorption, along with a substantial effective doping level to guarantee the formation of dark conductivity (σ) and electron-transport capacity.
View Article and Find Full Text PDFNano Lett
January 2025
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
Robust bipolar devices based on exclusively ultrawide bandgap (UWBG) semiconductors are highly desired for advanced power electronics. The heterojunction strategy has been a prevailing method for fabricating a bipolar device due to the lack of effective bipolar doping in the same UWBG material. Here, we demonstrate a unique heterojunction design integrating the p-type diamond and n-type ε-GaO that achieves remarkable breakdown voltages surpassing 3000 V.
View Article and Find Full Text PDFPhys Rev Lett
September 2024
Institute for Quantum Matter and Department of Physics and Astronomy, John Hopkins University, Baltimore, Maryland 21218, USA.
The mechanism of superconductivity in materials with aborted ferroelectricity and its emergence out of a dilute metallic phase in systems like doped SrTiO_{3} is an outstanding issue in condensed matter physics. This dilute metal has anomalous properties that are both similar and different to those found in the normal state of other unconventional superconductors. For instance, T^{2} resistivity can be found at densities that are too small to allow current decay through electron-electron scattering.
View Article and Find Full Text PDFJ Chem Phys
September 2024
James Franck Institute, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA.
Room temperature 6 μm intraband cascade electroluminescence (EL) is demonstrated with lightly n-doped HgTe colloidal quantum dots of ∼8 nm diameter deposited on interdigitated electrodes in a metal-insulator-metal device. With quantum dot films of ∼150 nm thickness made by solid-state-ligand-exchange, the devices emit at 1600 cm-1 (6.25 μm), with a spectral width of 200 cm-1, determined by the overlap of the 1Se-1Pe intraband transition of the quantum dots and the substrate photonic resonance.
View Article and Find Full Text PDFSmall
December 2024
Department of Mechanical Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
An electron transport layer (ETL) for highly efficient perovskite solar cells (PSCs) should exhibit superior electrical transport properties and have its band levels aligned with interfacing layers to ensure efficient extraction of photo-generated carriers. Nitrogen-doped TiO (TiO:N) is considered a promising ETL because it offers higher electrical conductivity compared to conventional ETLs made from spray-pyrolyzed TiO. However, the application of highly doped TiO:N in PSCs is often limited by the misalignment of energy band levels with adjacent layers and reduced optical transparency.
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