Strain-Induced Proximity Effect Creates Tunable Flat Bands in Diamond Chains

The pursuit of flat bands in materials science holds promise for creating exotic electronic states and potentially realising high-temperature superconductivity, and now researchers are exploring new ways to engineer these unusual energy landscapes. K Shivanand Thakur, Vihodi Theuno, both from Nagaland University, and Amrita Mukherjee from the Tata Institute of Fundamental Research, alongside Biplab Pal and colleagues, demonstrate a novel method for generating and controlling multiple flat bands within a specifically designed ‘decorated diamond chain’ structure. Their work reveals that applying strain to induce interactions between atoms within the chain allows precise control over the formation of both gapless and gapped flat bands, a significant advance over previous approaches that rely on magnetic fields. Importantly, the team shows these flat bands are remarkably stable even with imperfections in the material, and they exhibit nontrivial topological properties, suggesting potential applications in robust quantum technologies and opening avenues for experimental realisation using existing laser-based techniques.

A decorated diamond chain exhibits unique electronic properties arising from a strain-induced proximity effect between the diagonal sites of each diamond plaquette. This mechanism differs significantly from conventional diamond chains, where flat bands typically emerge from the influence of external magnetic fields. The research focuses on exploiting this strain-induced proximity effect to systematically control the hopping of electrons between atoms within the chain, enabling the creation of both gapless and gapped flat bands in the energy spectrum. The ability to engineer these flat bands holds potential for novel electronic devices and materials.

Non-Hermitian Flatband Topological Photonics Demonstrated

Researchers have demonstrated a new approach to controlling light using non-Hermitian topological photonics, a field that explores how to manipulate light waves in unconventional ways. The team focused on systems exhibiting “flatbands”, special energy states where light becomes localized and can be precisely controlled. By incorporating gain and loss into the system, a concept known as non-Hermitian physics, they achieved tunable topological phases and robust waveguiding, allowing for the creation of devices where light is confined and directed with minimal loss, even in the presence of imperfections. The research centers on higher-order topological insulators (HOTIs), materials that confine light not just to surfaces, but to corners and hinges.

By carefully adjusting the gain and loss parameters, the researchers demonstrated the ability to tune the topological phases of the system, controlling the location and behavior of these confined light waves. The study confirms the existence of robust topological edge and corner states, protected from disorder and imperfections, making them ideal for practical applications. The work relies heavily on theoretical and computational modeling, employing tight-binding models and band structure calculations to understand the behavior of light within the system. Numerical simulations were used to verify the theoretical predictions and explore the system’s properties in detail. The team suggests that future research could focus on experimentally verifying these predictions, designing specific photonic devices, and exploring the effects of nonlinearity and dynamic behavior within the system.

Tuning Flat Bands with Atomic Proximity Effects

Researchers have discovered a novel method for generating and controlling multiple “flat bands” within a specially designed diamond-shaped atomic lattice. Unlike conventional approaches where flat bands arise from magnetic fields, this technique utilizes a “proximity effect”, a subtle interaction between atoms within the lattice, to precisely tune the electronic properties of the material. By manipulating the interactions between specific atoms, the team demonstrated the ability to create both gapless and gapped flat bands, offering a new level of control over these unusual energy states. Gapless flat bands allow electrons to move freely at a specific energy level, while gapped bands create an energy barrier, isolating the electrons.

This control is achieved by carefully adjusting the “hopping” of electrons between atoms, effectively reshaping the energy landscape within the material. Importantly, the system consistently maintains a robust flat band at zero energy, regardless of the adjustments made. This ability to engineer multiple, tunable flat bands represents a significant advancement, as these bands are known to host exotic quantum phenomena. Flat bands are crucial for realizing strongly correlated electron systems, where interactions between electrons dominate their behavior, and are promising candidates for high-temperature superconductivity and novel magnetic states. Furthermore, the ability to precisely control flat bands opens doors for designing materials with tailored electronic properties, potentially leading to more efficient solar cells, advanced sensors, and revolutionary quantum devices. The method offers a pathway to experimentally realize these materials using laser-induced lattice platforms.

Strain-Induced Flat Bands and Topological States

This research demonstrates a novel method for generating and controlling multiple flat bands within a decorated diamond chain, achieved through a strain-induced proximity effect that alters the coupling between sites within the structure. This technique allows systematic control over the formation of both gapless and gapped flat bands, confirmed by analysis of localized states. The study establishes that these flat bands exhibit robustness even when subjected to minor amounts of random disorder, suggesting potential for practical applications. Furthermore, the research classifies the topological properties of this system, identifying edge states within the gapped energy spectrum.

These findings indicate the potential for creating devices based on quantum technologies, and the simplicity of the proposed lattice model makes it readily achievable in experiments using laser-induced photonic lattices. The authors also explored the impact of vertical diagonal coupling, revealing that a single flat band can be precisely positioned by adjusting this parameter. Future work could explore the full parameter space and investigate the potential for manipulating these flat bands for specific quantum applications. This research offers a promising pathway towards realizing novel materials with tailored electronic properties and exploring the fundamental physics of strongly correlated electron systems. The combination of theoretical analysis, computational modeling, and experimental feasibility makes this a significant contribution to the field of condensed matter physics.