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Zeroth-order fine-tuning eliminates explicit back-propagation and reduces memory overhead for large language models (LLMs), making it a promising approach for on-device fine-tuning tasks. However, existing memory-centric accelerators fail to fully leverage these benefits due to inefficiencies in balancing bit density, compute-in-memory capability, and endurance-retention trade-off. We present a reliability-aware, analog multi-level-cell (MLC) eDRAM-RRAM compute-in-memory (CIM) solution co-designed with zeroth-order optimization for language model fine-tuning. An RRAM-assisted eDRAM MLC programming scheme is developed, along with a process-voltage-temperature (PVT)-robust, large-sensing-window time-to-digital converter (TDC). The MLC-eDRAM integrating two-finger MOM provides 12× improvement in bit density over state-of-the-art MLC design. Another 5× density and 2× retention benefits are gained by adopting BEOL In2O3 FETs. 

Polarons, quasiparticles from electron-phonon coupling, are crucial for material properties including high-temperature superconductivity and colossal magnetoresistance. However, scarce studies have investigated polaron formation in low-dimensional materials with phonon polarity and electronic structure transitions. In this work, we studied polarons of tellurene, composed of chiral Te chains. The frequency and linewidth of the A₁phonon, which becomes increasingly polar for thinner tellurene, change abruptly for thickness below 10 nanometers, where field-effect mobility drops rapidly. These phonon and transport signatures, combined with phonon polarity and band structure, suggest a crossover from large polarons in bulk tellurium to small polarons in few-layer tellurene. Effective field theory considering phonon renormalization in the small-polaron regime semiquantitatively reproduces the phonon hardening and broadening effects. This polaron crossover stems from the quasi–one-dimensional nature of tellurene, where modulation of interchain distance reduces dielectric screening and promotes electron-phonon coupling. Our work provides valuable insights into the influence of polarons on phononic, electronic, and structural properties in low-dimensional materials. 

Abstract Relativistic Weyl fermion quasiparticles in Weyl semimetal bring the electron’s chirality degree of freedom into the electrical transport and give rise to exotic phenomena. A topological phase transition from a topological trivial phase to a topological non-trivial phase offers a route to control electronic devices through its topological properties. Here, we report the Weyl semimetal phase in hydrothermally grown two-dimensional Tellurium (2D Te) induced by high hydrostatic pressure (up to 2.47 GPa). The unique chiral crystal structure gives rise to chiral fermions with different topological chiral charges ($${{C}}=-{{1}},+{{1}},{{and}}-{{2}}$$ $C=-1,+1,and-2$). The highly tunable chemical potential in 2D Te provides comprehensive information for understanding the pressure-dependent electron band structure. The pressure-induced insulator-to-metal transition, two-carrier transport, and the non-trivial π Berry phase shift in quantum oscillations are observed in the 2D Te Weyl semimetal phase. Our work demonstrates the pressure-induced bandgap closing in the inversion asymmetric narrow bandgap semiconductor 2D Te.